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Roman Bek

Dr.

Wissenschaftlicher Mitarbeiter
Institut für Halbleiteroptik und Funktionelle Grenzflächen
Semiconductor Epitaxy Group

Contact

+49 711 685 69849
Email

Allmandring 3
70569 Stuttgart
Deutschland
Room: 1.003

Publications

2024
1. Strobel, T., Kazmaier, S., Bauer, T., Schäfer, M., Choudhary, A., Sharma, N. L., Joos, R., Nawrath, C., Weber, J. H., Nie, W., Bhayani, G., Wagner, L., Bisquerra, A., Geitz, M., Braun, R.-P., Hopfmann, C., Portalupi, S. L., Becher, C., & Michler, P. (2024). High-fidelity distribution of triggered polarization-entangled telecom photons via a 36 km intra-city fiber network. Optica Quantum, 2(4), Article 4. https://doi.org/10.1364/OPTICAQ.530838
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  @article{Strobel:24, abstract = {Fiber-based distribution of triggered, entangled, single-photon pairs is a key requirement for the future development of terrestrial quantum networks. In this context, semiconductor quantum dots (QDs) are promising candidates for deterministic sources of on-demand polarization-entangled photon pairs. So far, the best QD polarization-entangled-pair sources emit in the near-infrared wavelength regime, where the transmission distance in deployed fibers is limited. Here, to be compatible with existing fiber network infrastructures, bi-directional polarization-conserving quantum frequency conversion (QFC) is employed to convert the QD emission from 780 nm to telecom wavelengths. We show the preservation of polarization entanglement after QFC (fidelity to Bell state F $\varphi$ $+$,c o n v $=$0.972{\textpm}0.003) of the biexciton transition. As a step toward real-world applicability, high entanglement fidelities (F $\varphi$ $+$,l o o p $=$0.945{\textpm}0.005) after the propagation of one photon of the entangled pair along a 35.8 km field-installed standard single mode fiber link are reported. Furthermore, we successfully demonstrate a second polarization-conserving QFC step back to 780 nm preserving entanglement (F $\varphi$ $+$,b a c k $=$0.903{\textpm}0.005). This further prepares the way for interfacing quantum light to various quantum memories.}, author = {Strobel, Tim and Kazmaier, Stefan and Bauer, Tobias and Sch\"{a}fer, Marlon and Choudhary, Ankita and Sharma, Nand Lal and Joos, Raphael and Nawrath, Cornelius and Weber, Jonas H. and Nie, Weijie and Bhayani, Ghata and Wagner, Lukas and Bisquerra, Andr\'{e} and Geitz, Marc and Braun, Ralf-Peter and Hopfmann, Caspar and Portalupi, Simone L. and Becher, Christoph and Michler, Peter}, doi = {10.1364/OPTICAQ.530838}, journal = {Optica Quantum}, month = {08}, number = 4, pages = {274--281}, publisher = {Optica Publishing Group}, title = {High-fidelity distribution of triggered polarization-entangled telecom photons via a 36 km intra-city fiber network}, url = {https://opg.optica.org/opticaq/abstract.cfm?URI=opticaq-2-4-274}, volume = 2, year = 2024 }
  Link
  https://opg.optica.org/opticaq/abstract.cfm?URI=opticaq-2-4-274
2023
1. Engel, L., Kolatschek, S., Herzog, T., Vollmer, S., Jetter, M., Portalupi, S. L., & Michler, P. (2023). Purcell enhanced single-photon emission from a quantum dot coupled to a truncated Gaussian microcavity. Applied Physics Letters, 122(4), Article 4. https://doi.org/10.1063/5.0128631
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  @article{doi:10.1063/5.0128631, abstract = { Purcell enhancement of quantum dot (QD) single-photon emission and increased device brightness have been demonstrated with various types of microcavities. Here, we present the first realization of a truncated Gaussian-shaped microcavity coupled to a QD. The implementation is based on wet-chemical etching and epitaxial semiconductor overgrowth. The cavity modes and their spatial profiles are experimentally studied and agree well with simulations. The fundamental mode wavelength with Q-factors around 6000 and a small polarization splitting of 29 μeV can be reproducibly controlled via fabrication design, enabling the adaption of the cavity to a specific QD. Finally, transitions of a QD inside a cavity are tuned on and off resonance via temperature tuning. A reduced decay time by a factor above 3 on resonance clearly indicates Purcell enhancement while second-order correlation measurements of g(2)(0) = 0.057 prove that the QDs single-photon characteristic is preserved. }, author = {Engel, Lena and Kolatschek, Sascha and Herzog, Thomas and Vollmer, Sergej and Jetter, Michael and Portalupi, Simone L. and Michler, Peter}, doi = {10.1063/5.0128631}, eprint = {https://doi.org/10.1063/5.0128631}, journal = {Applied Physics Letters}, number = 4, pages = 043503, title = {Purcell enhanced single-photon emission from a quantum dot coupled to a truncated Gaussian microcavity}, url = {/brokenurl# https://doi.org/10.1063/5.0128631 }, volume = 122, year = 2023 }
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  /brokenurl# https://doi.org/10.1063/5.0128631
2. Abbas, R. A., Sabry, Y. M., Omran, H., Huang, Z., Zimmer, M., Jetter, M., Michler, P., & Khalil, D. (2023). Modelling and experimental characterization of double layer InP/AlGaInP quantum dot laser. Optical and Quantum Electronics, 56(2), Article 2. https://doi.org/10.1007/s11082-023-05276-9
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  @article{Abbas2023, abstract = {Spectrum of an InP/AlGaInP self- assembled double-layer quantum dot (QD) laser fabricated by metal--organic vapor-phase epitaxy is theoretically and experimentally investigated. A bimodal QD size distribution (small and large QD groups) was detected which is formed during the fabrication. A model is proposed based on rate equations accounting for the superposition of two inhomogeneous QD groups. The total output power and the power spectral density (PSD) of the fabricated QD laser are experimentally characterized at room temperature. The output spectrum is segmented into the sum of two Gaussians curves (super Gaussian) belonging to the small and large QD groups. The peak PSD and the spectral width of each group are extracted and their dependency on the injected current density is analysed. The peak of the large QDs is found to be dominant at small current while the peak of the small QDs dominated at high current alongside a reduction in its spectral width leading to lasing based on them. This behaviour is attributed to the saturation of the large QDs energy levels due to its relatively long radiative lifetime. The experimental analysis is in a good agreement with the theoretical results.}, author = {Abbas, Radwa A. and Sabry, Yasser M. and Omran, Haitham and Huang, Zhihua and Zimmer, Michael and Jetter, Michael and Michler, Peter and Khalil, Diaa}, day = 14, doi = {10.1007/s11082-023-05276-9}, issn = {1572-817X}, journal = {Optical and Quantum Electronics}, month = {12}, number = 2, pages = 205, title = {Modelling and experimental characterization of double layer InP/AlGaInP quantum dot laser}, url = {https://doi.org/10.1007/s11082-023-05276-9}, volume = 56, year = 2023 }
  Link
  https://doi.org/10.1007/s11082-023-05276-9
2022
1. Bozzio, M., Vyvlecka, M., Cosacchi, M., Nawrath, C., Seidelmann, T., Loredo, J. C., Portalupi, S. L., Axt, V. M., Michler, P., & Walther, P. (2022). Enhancing quantum cryptography with quantum dot single-photon sources. Npj Quantum Information, 8(1), Article 1. https://doi.org/10.1038/s41534-022-00626-z
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  @article{Bozzio2022, abstract = {Quantum cryptography harnesses quantum light, in particular single photons, to provide security guarantees that cannot be reached by classical means. For each cryptographic task, the security feature of interest is directly related to the photons' non-classical properties. Quantum dot-based single-photon sources are remarkable candidates, as they can in principle emit deterministically, with high brightness and low multiphoton contribution. Here, we show that these sources provide additional security benefits, thanks to the tunability of coherence in the emitted photon-number states. We identify the optimal optical pumping scheme for the main quantum-cryptographic primitives, and benchmark their performance with respect to Poisson-distributed sources such as attenuated laser states and down-conversion sources. In particular, we elaborate on the advantage of using phonon-assisted and two-photon excitation rather than resonant excitation for quantum key distribution and other primitives. The presented results will guide future developments in solid-state and quantum information science for photon sources that are tailored to quantum communication tasks.}, author = {Bozzio, Mathieu and Vyvlecka, Michal and Cosacchi, Michael and Nawrath, Cornelius and Seidelmann, Tim and Loredo, Juan C. and Portalupi, Simone L. and Axt, Vollrath M. and Michler, Peter and Walther, Philip}, day = 08, doi = {10.1038/s41534-022-00626-z}, issn = {2056-6387}, journal = {npj Quantum Information}, month = {09}, number = 1, pages = 104, title = {Enhancing quantum cryptography with quantum dot single-photon sources}, url = {https://doi.org/10.1038/s41534-022-00626-z}, volume = 8, year = 2022 }
  Link
  https://doi.org/10.1038/s41534-022-00626-z
2. Dusanowski, Ł., Nawrath, C., Portalupi, S. L., Jetter, M., Huber, T., Klembt, S., Michler, P., & Höfling, S. (2022). Optical charge injection and coherent control of a quantum-dot spin-qubit emitting at telecom wavelengths. Nature Communications, 13(1), Article 1. https://doi.org/10.1038/s41467-022-28328-2
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  @article{Dusanowski2022, abstract = {Solid-state quantum emitters with manipulable spin-qubits are promising platforms for quantum communication applications. Although such light-matter interfaces could be realized in many systems only a few allow for light emission in the telecom bands necessary for long-distance quantum networks. Here, we propose and implement an optically active solid-state spin-qubit based on a hole confined in a single InAs/GaAs quantum dot grown on an InGaAs metamorphic buffer layer emitting photons in the C-band. We lift the hole spin-degeneracy using an external magnetic field and demonstrate hole injection, initialization, read-out and complete coherent control using picosecond optical pulses. These results showcase a solid-state spin-qubit platform compatible with preexisting optical fiber networks.}, author = {Dusanowski, {\L}ukasz and Nawrath, Cornelius and Portalupi, Simone L. and Jetter, Michael and Huber, Tobias and Klembt, Sebastian and Michler, Peter and H{\"o}fling, Sven}, day = 08, doi = {10.1038/s41467-022-28328-2}, issn = {2041-1723}, journal = {Nature Communications}, month = {02}, number = 1, pages = 748, title = {Optical charge injection and coherent control of a quantum-dot spin-qubit emitting at telecom wavelengths}, url = {https://doi.org/10.1038/s41467-022-28328-2}, volume = 13, year = 2022 }
  Link
  https://doi.org/10.1038/s41467-022-28328-2
3. Woods, J. R. C., Gorecki, J., Bek, R., Richardson, S. C., Daykin, J., Hooper, G., Branagan-Harris, E., Tropper, A. C., Wilkinson, J. S., Jetter, M., Michler, P., & Apostolopoulos, V. (2022). Coherent waveguide laser arrays in semiconductor quantum well membranes. Opt. Express, 30(18), Article 18. https://doi.org/10.1364/OE.457577
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  @article{Woods:22, abstract = {Coherent laser arrays compatible with silicon photonics are demonstrated in a waveguide geometry in epitaxially grown semiconductor membrane quantum well lasers transferred on substrates of silicon carbide and oxidised silicon; we record lasing thresholds as low as 60 mW of pump power. We study the emission of single lasers and arrays of lasers in the sub-mm range. We are able to create waveguide laser arrays with modal widths of approximately 5 {\textminus} 10 {\textmu}m separated by 10 {\textminus} 20 {\textmu}m, using real and reciprocal space imaging we study their emission characteristics and find that they maintain their mutual coherence while operating on either single or multiple longitudinal modes per lasing cavity.}, author = {Woods, Jonathan R. C. and Gorecki, Jon and Bek, Roman and Richardson, Stephen C. and Daykin, Jake and Hooper, Grace and Branagan-Harris, Emelia and Tropper, Anne C. and Wilkinson, James S. and Jetter, Michael and Michler, Peter and Apostolopoulos, Vasilis}, doi = {10.1364/OE.457577}, journal = {Opt. Express}, month = {08}, number = 18, pages = {32174--32188}, publisher = {Optica Publishing Group}, title = {Coherent waveguide laser arrays in semiconductor quantum well membranes}, url = {http://opg.optica.org/oe/abstract.cfm?URI=oe-30-18-32174}, volume = 30, year = 2022 }
  Link
  http://opg.optica.org/oe/abstract.cfm?URI=oe-30-18-32174
4. Grossmann, M., Jetter, M., & Michler, P. (2022). Nonlinear reflectivity of AlGaInP SESAMs for mode locking in the red spectral range. Opt. Express, 30(12), Article 12. https://doi.org/10.1364/OE.453638
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  @article{Grossmann:22, abstract = {Mode-locked vertical external-cavity semiconductor lasers (VECSELs) are a wavelength-versatile laser that relies on a semiconductor saturable absorber mirror (SESAM) to initiate pulsed emission while simultaneously significantly influencing the pulse\&\#x2019;s properties. A SESAM can be characterized using a nonlinear reflectivity setup, realized here in the red spectral range around 660\&\#x2009;nm and achieving a moderate peak-to-peak variation of 0.17\&\#x0025;. We use our home-built mode-locked VECSEL to reach a high maximum fluence up to 430\&\#x2005;\&\#x00B5;J/cm2 with strongly chirped 7.5\&\#x2009;ps pulses. This allows the first-of-its-kind characterization of GaInP quantum well SESAMs, thereby revealing saturation fluences of 38\&\#x2005;\&\#x00B5;J/cm2 and 34\&\#x2005;\&\#x00B5;J/cm2 with modulation depths of 5\&\#x0025; and 10.3\&\#x0025; for SESAMs comprising one or two active quantum wells, respectively. For all structures, a nonsaturable loss of 2.8\&\#x0025; is found and attributed to scattering loss.}, author = {Grossmann, M. and Jetter, M. and Michler, P.}, doi = {10.1364/OE.453638}, journal = {Opt. Express}, month = {06}, number = 12, pages = {20943--20951}, publisher = {Optica Publishing Group}, title = {Nonlinear reflectivity of AlGaInP SESAMs for mode locking in the red spectral range}, url = {http://opg.optica.org/oe/abstract.cfm?URI=oe-30-12-20943}, volume = 30, year = 2022 }
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  http://opg.optica.org/oe/abstract.cfm?URI=oe-30-12-20943
2021
1. Wang, Q., Maisch, J., Tang, F., Zhao, D., Yang, S., Joos, R., Portalupi, S. L., Michler, P., & Smet, J. H. (2021). Highly Polarized Single Photons from Strain-Induced Quasi-1D Localized Excitons in WSe2. Nano Letters, 21(17), Article 17. https://doi.org/10.1021/acs.nanolett.1c01927
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  @article{doi:10.1021/acs.nanolett.1c01927, abstract = { Single photon emission from localized excitons in two-dimensional (2D) materials has been extensively investigated because of its relevance for quantum information applications. Prerequisites are the availability of photons with high purity polarization and controllable polarization orientation that can be integrated with optical cavities. Here, deformation strain along edges of prepatterned square-shaped substrate protrusions is exploited to induce quasi-one-dimensional (1D) localized excitons in WSe2 monolayers as an elegant way to get photons that fulfill these requirements. At zero magnetic field, the emission is linearly polarized with 95\% purity because exciton states are valley hybridized with equal shares of both valleys and predominant emission from excitons with a dipole moment along the elongated direction. In a strong field, one valley is favored and the linear polarization is converted to high-purity circular polarization. This deterministic control over polarization purity and orientation is a valuable asset in the context of integrated quantum photonics. }, author = {Wang, Qixing and Maisch, Julian and Tang, Fangdong and Zhao, Dong and Yang, Sheng and Joos, Raphael and Portalupi, Simone Luca and Michler, Peter and Smet, Jurgen H.}, doi = {10.1021/acs.nanolett.1c01927}, eprint = {https://doi.org/10.1021/acs.nanolett.1c01927}, journal = {Nano Letters}, note = {PMID: 34424710}, number = 17, pages = {7175-7182}, title = {Highly Polarized Single Photons from Strain-Induced Quasi-1D Localized Excitons in WSe2}, url = {/brokenurl# https://doi.org/10.1021/acs.nanolett.1c01927 }, volume = 21, year = 2021 }
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  /brokenurl# https://doi.org/10.1021/acs.nanolett.1c01927
2. Bek, E., Jetter, M., & Michler, P. (2021). Mode-locked AlGaInP VECSEL for the red and UV spectral range: Vol. In Vertical External Cavity Surface Emitting Lasers – VECSEL Technology and Applications. Wiley-VCH, Weinheim, 305 – 320.
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  @book{bek2021modelocked, author = {Bek, E and Jetter, M and Michler, P}, publisher = {Wiley-VCH, Weinheim, 305 – 320}, title = {Mode-locked AlGaInP VECSEL for the red and UV spectral range}, volume = {In Vertical External Cavity Surface Emitting Lasers – VECSEL Technology and Applications}, year = 2021 }
2020
1. van Loock, P., Alt, W., Becher, C., Benson, O., Boche, H., Deppe, C., Eschner, J., Höfling, S., Meschede, D., Michler, P., Schmidt, F., & Weinfurter, H. (2020). Extending Quantum Links: Modules for Fiber- and Memory-Based Quantum Repeaters. http://arxiv.org/abs/1912.10123
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  @article{vanloock2019extending, abstract = {We analyze elementary building blocks for quantum repeaters based on fiber channels and memory stations. Implementations are considered for three different physical platforms, for which suitable components are available: quantum dots, trapped atoms and ions, and color centers in diamond. We evaluate and compare the performances of basic quantum repeater links for these platforms both for present-day, state-of-the-art experimental parameters as well as for parameters that could in principle be reached in the future. The ultimate goal is to experimentally explore regimes at intermediate distances, up to a few 100 km, in which the repeater-assisted secret key transmission rates exceed the maximal rate achievable via direct transmission. We consider two different protocols, one of which is better adapted to the higher source clock rate and lower memory coherence time of the quantum dot platform, while the other circumvents the need of writing photonic quantum states into the memories in a heralded, non-destructive fashion. The elementary building blocks and protocols can be connected in a modular form to construct a quantum repeater system that is potentially scalable to large distances.}, author = {van Loock, Peter and Alt, Wolfgang and Becher, Christoph and Benson, Oliver and Boche, Holger and Deppe, Christian and Eschner, Jürgen and Höfling, Sven and Meschede, Dieter and Michler, Peter and Schmidt, Frank and Weinfurter, Harald}, note = {cite arxiv:1912.10123Comment: 48 pages in Word style, "White Paper" of Q.Link.X Consortium}, title = {Extending Quantum Links: Modules for Fiber- and Memory-Based Quantum Repeaters}, url = {http://arxiv.org/abs/1912.10123}, year = 2020 }
  Link
  http://arxiv.org/abs/1912.10123
2. Kriso, C., Kress, S., Munshi, T., Grossmann, M., Bek, R., Jetter, M., Michler, P., Stolz, W., Koch, M., & Rahimi-Iman, A. (2020). Wavelength and Pump-Power Dependent Nonlinear Refraction and Absorption in a Semiconductor Disk Laser. IEEE Photonics Technology Letters, 32(2), Article 2. https://doi.org/10.1109/LPT.2019.2957875
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  @article{8931586, abstract = {We characterize both nonlinear refraction and absorption in a vertical-external-cavity surface-emitting laser (VECSEL) as a function of pump irradiance over the whole range of lasing wavelengths. We observe an approximately linear decrease in magnitude for both nonlinear refraction and nonlinear absorption with optical pumping when the thermally induced shift of the lasing wavelength is considered. Our results are of particular significance for understanding self-modelocking of VECSELs which might be driven by nonlinear lensing.}, author = {{Kriso}, C. and {Kress}, S. and {Munshi}, T. and {Grossmann}, M. and {Bek}, R. and {Jetter}, M. and {Michler}, P. and {Stolz}, W. and {Koch}, M. and {Rahimi-Iman}, A.}, doi = {10.1109/LPT.2019.2957875}, issn = {1941-0174}, journal = {IEEE Photonics Technology Letters}, month = {01}, number = 2, pages = {85-88}, title = {Wavelength and Pump-Power Dependent Nonlinear Refraction and Absorption in a Semiconductor Disk Laser}, url = {https://ieeexplore.ieee.org/document/8931586}, volume = 32, year = 2020 }
  Link
  https://ieeexplore.ieee.org/document/8931586
3. Maisch, J., Vural, H., Jetter, M., Gerhardt, I., Portalupi, S., & Michler, P. (2020). Controllable Delay and Polarization Routing of Single Photons. Advaced Quatum Technologies. https://doi.org/201900057
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  @article{noauthororeditor, abstract = {Full control of single photons is important in quantum information and quantum networking. In particular, controlling the photon–atom interaction can be an appealing means to realize more complex quantum experiments. As a matter of example, the storage of photons into atomic media represents one key approach to memory‐assisted quantum communication and computing. Here it is shown that the propagation of single photons from a semiconductor quantum dot can be deliberately controlled by an atomic vapor under the application of an external magnetic field. The present results enable the use of an atomic vapor as a precise and reliable wavelength selective delay and allows for routing the single photons according to their polarization and the external magnetic field. With an overall delay of 25 ns, it is possible to fine‐tune the arrival time of the photons by more than 600 ps which matches the scale of the quantum dot's lifetime. The experimental data are fully reproduced by a theoretical model.}, author = {Maisch, Julian and Vural, Hüseyin and Jetter, Michael and Gerhardt, Ilja and Portalupi, Simone and Michler, Peter}, doi = {201900057}, journal = {Advaced Quatum Technologies}, language = {english}, title = {Controllable Delay and Polarization Routing of Single Photons}, url = {https://doi.org/10.1002/qute.201900057}, year = 2020 }
  Link
  https://doi.org/10.1002/qute.201900057
4. Großmann, M., Bek, R., Jetter, M., & Michler, P. (2020). Stable fundamental and dual-pulse mode locking of red-emitting VECSELs. Laser Physics Letters, 17(6), Article 6. https://iopscience.iop.org/article/10.1088/1612-202X/ab881f/meta
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  @article{noauthororeditor, abstract = {We present a thorough characterization of a red-emitting mode-locked semiconductor disk laser producing the first stable fundamental mode-locked pulse train in the red spectral range. The achievable temporal FWHM pulse length of the Lorentzian-shaped pulses is just below 3$\,\mathrm{ps}$ which represents the shortest pulses obtained in a fully-resonant absorber and gain structure design. We also include an intracavity birefringent filter to stabilize and tune the emission wavelength between $667\ \mathrm{nm}$ and $675\ \mathrm{nm}$. This, in combination with a real-time sampling of the emitted pulse train, allows us to distinguish three regimes according to their round-trip dynamics. The first regime resembles stable fundamental mode locking and is observed for wavelengths below $670\ \mathrm{nm}$ while for an emission wavelength of $675\ \mathrm{nm}$ the continuous wave regime is observed. These two operating regimes enclose the dual-pulse mode locking regime appearing between $670\ \mathrm{nm}$ and $675\ \mathrm{nm}$. This regime is characterized by an energy exchange between the individual pulses of the dual-pulse mode locking regime and we clearly relate the side-peaks in the radio frequency spectrum to the dual-pulse energy-exchange frequency and the temporal interpulse spacing to the individual arm lengths of the gain-folded external cavity. Overall, we attribute these different operating regimes to near-bandgap operation of the SESAM which allows for dispersion of saturation fluence and modulation depth.}, author = {Großmann, Marius and Bek, Roman and Jetter, Michael and Michler, Peter}, journal = {Laser Physics Letters}, language = {english}, number = 6, title = {Stable fundamental and dual-pulse mode locking of red-emitting VECSELs}, url = {https://iopscience.iop.org/article/10.1088/1612-202X/ab881f/meta}, volume = 17, year = 2020 }
  Link
  https://iopscience.iop.org/article/10.1088/1612-202X/ab881f/meta
5. Vural, H., Portalupi, S., & Michler, P. (2020). Perspective of self-assembled InGaAs quantum-dots for multi-source quantum implementations. Applied Physics Letters, 117(3), Article 3. https://doi.org/10.1063/5.0010782
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  @article{noauthororeditor, abstract = {In recent years, semiconductor quantum dots have demonstrated their potential to reach the goal of being an ideal source of single and entangled photon pairs. Exciting reports of near unity entanglement fidelity, close to unity photon indistinguishability, and high collection efficiency in nanophotonic structures have been demonstrated by several distinct groups, showing unequivocally the maturity of this technology. To achieve the required complexity and scalability in realistic quantum photonic implementations, two-photon interference of photons from multi-sources must be reached. While high indistinguishability values have been observed for photons generated from the same source within a relatively short time separation, achieving similar visibility for larger time separation or in multi-source experiments still requires intensive efforts. In fact, the coupling to the particular mesoscopic environment of charge carriers confined in the quantum dot leads to decoherence processes, which limit the quantum interference effects to a short time window. Here, we discuss the progress in studying the dynamics of this decoherence, which crucially depends on the evolution of line broadening in high-quality self-assembled InGaAs quantum dots. Characterization of line broadening mechanisms is the first fundamental step to be able to counteract them. Optimization of the growth and active and passive control of the radiative transitions are crucial for the technological readiness of non-classical light sources based on semiconductor platforms. The non-classical emission properties of self-assembled semiconductor quantum dots (QDs), which render them one of the most appealing platforms for quantum photonics, were already demonstrated at the beginning of the millennium: the emission of triggered single photons1 and the indistinguishability of successively emitted photons.2 These two properties provide the basis for many quantum optical technologies,3–9 while utilizing resonant π‐ pulse excitation is a promising scheme to push QD emission to its best performance. High-performance deterministic sources10–12 can bring significant advantages to the realization of quantum information tasks in comparison to the utilization of probabilistic emitters.13 To shed light on the limitations these emitters still face, it is instructive to have a look at the milestone works on the path to ever better non-classical interference visibilities of QD photons. The first observation of Hong–Ou–Mandel (HOM) two-photon interference14 of successively emitted QD photons was reached under the resonant excitation of higher QD states2 and demonstrated a visibility of 0.8. However, this high degree of indistinguishability could not be justified by the measured coherence time of the photons by means of Fourier spectroscopy (FS). This suggested that emission line broadening mainly occurs at a much slower rate than the radiative decay. While the pure dephasing on the photons' wavepacket15 tends to vanish, a diffusion of emission frequency is present, which is below the spectral resolution of standard spectrometers, and its temporal dynamics cannot be resolved by standard FS.16,17 A continuous improvement in the non-classical properties of semiconductor quantum dots and their efficient integration in nanophotonic devices were achieved over the years.10,11,18 Following the first demonstration of non-classical interference for successively emitted QD photons, it took a decade to observe close to unity HOM interference visibility. This was reached by the combination of a high-quality sample and a proper pumping scheme: resonant excitation into the s-shell under the π‐ pulse.19 However, the emission spectrum still showed line broadening with a strong dependence on the excitation power in the investigated range of up to the π‐ pulse. In contrast, negligible reduction of HOM visibility with the pulse power implied that the fluctuation amplitude of the slower line broadening mechanism is indeed independent of the intrinsic photonic coherence. The next significant step was the demonstration of indistinguishable photons from a resonantly pumped QD embedded in a micropillar structure.20,21 In these devices, near unity visibility was shown not only for a time separation between successively emitted photons of a few nanoseconds but also for photons hundreds of nanoseconds22 or up to 15 μs (Ref. 23) apart. The additional high brightness of such a source allowed very recently demultiplexed multi-photon boson sampling, approaching the performance of classical computers.9 Further improvements in quantum optical applications and their scalability crucially depend on the understanding and control of the broadening processes, which limit HOM visibility and thus the quantum interference and fidelity of many applications. For a single emitter, the dynamics of these decoherence processes translates in the time-wise reduction of HOM visibility, which limits the achievable photon number in multi-photon applications. For independent multi-source applications, the full integrated spectra due to the total extent of broadening processes directly determine their quantum interference. Despite its determining character and crucial importance for the future technological readiness, the decoherence dynamics of single-photon emitters translating into the emission spectrum are rarely studied. Further below, after a short overview on the noise sources, we discuss the approaches to study the broadening dynamics and attempts dedicated to their stabilization (Fig. 1). figure FIG. 1. (a)–(c) Illustration of an electron-hole pair confined in a self-assembled quantum dot (QD) under environmental coupling of (a) lattice vibrations, (b) nuclear spins constituting an effective magnetic field Beff referred to as the Overhauser-field, and (c) local charges. Their fluctuations induce dephasing and emission line broadening over the indicated timescales. Δνi/ΔνFL is the ratio between common environment-induced broadening and the Fourier-limited homogeneous linewidth. (d)–(f) Illustration of active and passive counteracting approaches including (d) a quantum dot in a microcavity at cryogenic temperature, (e) an external magnetic field Bext and self-locking effects through dynamic nuclear spin polarization (DNSP), and (f) an external electric field Eext and active feedback control.}, author = {Vural, Hüseyin and Portalupi, Simone and Michler, Peter}, doi = {https://doi.org/10.1063/5.0010782}, journal = {Applied Physics Letters}, language = {engl}, number = 3, title = {Perspective of self-assembled InGaAs quantum-dots for multi-source quantum implementations}, url = {https://aip.scitation.org/doi/full/10.1063/5.0010782?journalCode=apl}, volume = 117, year = 2020 }
  Link
  https://aip.scitation.org/doi/full/10.1063/5.0010782?journalCode=apl
2019
1. Hepp, S., Jetter, M., Portalupi, S., & Michler, P. (2019). Semiconductor Quantum Dots for Integrated Quantum Photonics. Advanced Quantum Technologies. https://doi.org/10.1002/qute.201900020
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  @article{noauthororeditor, abstract = {Quantum mechanics promises to have a strong impact on many aspects of research and technology, improving classical analogues via purely quantum effects. A large variety of tasks are currently under investigation, for example, the implementation of quantum computing, sensing, metrology, and communication. From a general perspective, in a similar way as classical computing benefited by the reduction of the device footprint, enabling the realization of highly complex chips, a range of quantum applications will sensibly improve thanks to the successful realization of on‐chip quantum photonics. Conversely to bulky table‐top experiments, it would be very advantageous to transfer all required functionalities on the same quantum photonic chip. The key elements for quantum photonic circuits are on‐demand nonclassical light sources, a versatile photonic logic, the ability to store quantum information, and highly efficient detectors, directly integrated on‐chip. Among several systems capable of the efficient generation of single‐ and indistinguishable photons, quantum dots are rapidly establishing as one of the most appealing candidates. This paper reviews the recent progress in the on‐chip integration of quantum‐dot‐based nonclassical light sources as well as in the development of the main building blocks, either integrated monolithically or hybridly on a compact and scalable platform.}, author = {Hepp, Sefan and Jetter, Michael and Portalupi, Simone and Michler, Peter}, doi = {10.1002/qute.201900020}, journal = {Advanced Quantum Technologies}, language = {english}, month = {07}, title = {Semiconductor Quantum Dots for Integrated Quantum Photonics}, year = 2019 }
2. Schmidt, E., Reutter, E., Schwartz, M., Vural, H., Ilin, K., Jetter, M., Michler, P., & Siegel, M. (2019). Characterization of a photon-number resolving SNSPD using Poissonian and sub-Poissonian light. https://doi.org/10.1109/TASC.2019.2905566
  - BibTeX
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  BibTeX
  @article{schmidt2018characterization, abstract = {Photon-number resolving (PNR) single-photon detectors are of interest for a wide range of applications in the emerging field of photon based quantum technologies. Especially photonic integrated circuits will pave the way for a high complexity and ease of use of quantum photonics. Superconducting nanowire single-photon detectors (SNSPDs) are of special interest since they combine a high detection efficiency and a high timing accuracy with a high count rate and they can be configured as PNR-SNSPDs. Here, we present a PNR-SNSPD with a four photon resolution suitable for waveguide integration operating at a temperature of 4 K. A high statistical accuracy for the photon number is achieved for a Poissonian light source at a photon flux below 5 photons/pulse with a detection efficiency of 22.7 +- 3.0% at 900 nm and a pulse rate frequency of 76 MHz. We demonstrate the ability of such a detector to discriminate a sub-Poissonian from a Poissonian light source.}, author = {Schmidt, Ekkehart and Reutter, Eric and Schwartz, Mario and Vural, Hüseyin and Ilin, Konstantin and Jetter, Michael and Michler, Peter and Siegel, Michael}, doi = {10.1109/TASC.2019.2905566}, note = {cite arxiv:1810.11256}, title = {Characterization of a photon-number resolving SNSPD using Poissonian and sub-Poissonian light }, url = {http://arxiv.org/abs/1810.11256}, year = 2019 }
  Link
  http://arxiv.org/abs/1810.11256
3. Weber, J. H., Kambs, B., Kettler, J., Kern, S., Maisch, J., Vural, H., Jetter, M., Portalupi, S. L., Becher, C., & Michler, P. (2019). Two-photon interference in the telecom C-band after frequency conversion of photons from remote quantum emitters. Nature Nanotechnology, 14, 23–26. https://doi.org/10.1038/s41565-018-0279-8
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  BibTeX
  @article{weber2019twophoton, abstract = {Efficient fibre-based long-distance quantum communication via quantum repeaters relies on deterministic single-photon sources at telecom wavelengths, potentially exploiting the existing world-wide infrastructures. For upscaling the experimental complexity in quantum networking, two-photon interference (TPI) of remote non-classical emitters in the low-loss telecom bands is of utmost importance. Several experiments have been conducted regarding TPI of distinct emitters, for example, using trapped atoms1, ions2, nitrogen vacancy centres3,4, silicon vacancy centres5, organic molecules6 and semiconductor quantum dots7,8. However, the spectral range was far from the highly desirable telecom C-band. Here, we exploit quantum frequency conversion to realize TPI at 1,550 nm with single photons stemming from two remote quantum dots. We thereby prove quantum frequency conversion9–11 as a bridging technology and a precise and stable mechanism to erase the frequency difference between independent emitters. On resonance, a TPI visibility of 29 ± 3% has been observed, limited only by the spectral diffusion processes of the individual quantum dots12,13. The local fibre network used covers several rooms between two floors of the building. Even the addition of up to 2 km of fibre channel shows no influence on the TPI visibility, proving the photon wavepacket distortion to be negligible. Our studies pave the way to establish long-distance entanglement distribution between remote solid-state emitters including interfaces with various quantum hybrid systems14–16.}, author = {Weber, Jonas H. and Kambs, Benjamin and Kettler, Jan and Kern, Simon and Maisch, Julian and Vural, Hüseyin and Jetter, Michael and Portalupi, Simone L. and Becher, Christoph and Michler, Peter}, doi = {10.1038/s41565-018-0279-8}, issn = {17483395}, journal = {Nature Nanotechnology}, pages = {23-26}, refid = {Weber2018}, title = {Two-photon interference in the telecom C-band after frequency conversion of photons from remote quantum emitters}, url = {https://doi.org/10.1038/s41565-018-0279-8}, volume = 14, year = 2019 }
  Link
  https://doi.org/10.1038/s41565-018-0279-8
4. Kriso, C., Kress, S., Munshi, T., Grossmann, M., Bek, R., Jetter, M., Michler, P., Stolz, W., Koch, M., & Rahimi-Iman, A. (2019). Microcavity-enhanced Kerr nonlinearity in a vertical-external-cavity surface-emitting laser. Opt. Express, 27(9), Article 9. https://doi.org/10.1364/OE.27.011914
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  BibTeX
  @article{Kriso:19, abstract = {Self-mode-locking has become an emerging path to the generation of ultrashort pulses with vertical-external-cavity surface-emitting lasers. In our work, a strong Kerr nonlinearity that is so far assumed to give rise to mode-locked operation is evidenced and a strong nonlinearity enhancement by the microcavity is revealed. We present wavelength-dependent measurements of the nonlinear absorption and nonlinear refractive index change in a gain chip using the Z-scan technique. We report negative nonlinear refraction up to 5x10\&\#x2212;12\&\#x00A0;cm2/W in magnitude in the (InGa)As/Ga(AsP) material system close to the laser design wavelength, which can lead to Kerr lensing. We show that by changing the angle of incidence of the probe beam with respect to the gain chip, the Kerr nonlinearity can be wavelength-tuned, shifting with the microcavity resonance. Such findings may ultimately lead to novel concepts with regard to tailored self-mode-locking behavior achievable by peculiar Kerr-lens chip designs for cost-effective, robust and compact fs-pulsed semiconductor lasers.}, author = {Kriso, Christian and Kress, Sascha and Munshi, Tasnim and Grossmann, Marius and Bek, Roman and Jetter, Michael and Michler, Peter and Stolz, Wolfgang and Koch, Martin and Rahimi-Iman, Arash}, doi = {10.1364/OE.27.011914}, journal = {Opt. Express}, month = {04}, number = 9, pages = {11914--11929}, publisher = {OSA}, title = {Microcavity-enhanced Kerr nonlinearity in a vertical-external-cavity surface-emitting laser}, url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-27-9-11914}, volume = 27, year = 2019 }
  Link
  http://www.opticsexpress.org/abstract.cfm?URI=oe-27-9-11914
5. Portalupi, S., Jetter, M., & Michler, P. (2019). InAs quantum dots grown on metamorphic buffers as non-classical light sources at telecom C-band: a review. Semicond. Sci. Technol, 34(5), Article 5. https://iopscience.iop.org/article/10.1088/1361-6641/ab08b4
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  @article{noauthororeditor, abstract = {Long-distance quantum communication and computation is based on the exchange of information via photons as flying qubits. In all foreseen implementations, from quantum relays and networks to remote quantum computing, the photons must be able to propagate over long distances, in silica fibers, with limited absorption and wave packet dispersion. When propagating into silica fibers, photons in the so-called telecom C-band (i.e. wavelength around 1550 nm) will experience the absolute minimum of absorption, together with a limited photon wave packet dispersion. This implies that losses of information will be minimized and additionally, the capability of the photons to quantum interfere (the so-called Hong–Ou–Mandel effect) will be negligibly affected. This motivated the search for efficient non-classical light sources in this wavelength range. In the present review, we discuss the approaches followed to red-shift the emission wavelength from the near-infrared (NIR) to telecom wavelengths. In particular, the use of metamorphic buffers (MMBs) enabled the use of highly developed InAs/GaAs systems, engineering the dots to emit single and entangled photons in the telecom C-band. The main advantage of this approach is set by the choice of the material system: being the same as state-of-the-art structures emitting in the NIR range, it opens the possibility of achieving comparable performances even at telecommunication wavelengths. Here we will discuss the current state-of-the-art in the generation of non-classical photons, comparing the properties and performances of MMB-based results with other competing quantum dot (QD) platforms. We report in particular that very low fine-structure splitting can be observed with conservative values, on average well below 10 μeV. This allowed for the observation of post-selected entanglement fidelity higher than 0.6. Additionally, on-demand single-photon emission with ${g}_{(0)}^{2}=0.184\pm 0.002$ was observed in addition to a very low emitter density of $\approx {10}^{7}\,{\mathrm{cm}}^{-2}$ and a decay time of τ ≈ 1.2 ns comparable to standard InAs QDs emitting in the NIR range. A final highlight on approaches to further improve the current device performances will also be reported.}, author = {Portalupi, Simone and Jetter, Michael and Michler, Peter}, journal = {Semicond. Sci. Technol}, language = {english}, month = {04}, number = 5, title = {InAs quantum dots grown on metamorphic buffers as non-classical light sources at telecom C-band: a review}, url = {https://iopscience.iop.org/article/10.1088/1361-6641/ab08b4}, volume = 34, year = 2019 }
  Link
  https://iopscience.iop.org/article/10.1088/1361-6641/ab08b4
2018
1. Sartison, M., Engel, L., Kolatschek, S., Olbrich, F., Nawrath, C., Hepp, S., Jetter, M., Michler, P., & Portalupi, S. L. (2018). Deterministic integration and optical characterization of telecom O-band quantum dots embedded into wet-chemically etched Gaussian-shaped microlenses. Appl. Phys. Lett., 113(3), Article 3. https://doi.org/10.1063/1.5038271
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  @article{sartison2018deterministic, abstract = {In the present study, we report on the deterministic integration of quantum dots, emitting in the telecom O-band, into wet-chemically fabricated Gaussian-shaped microlenses which exhibit a surface quality comparable to epi-ready wafers. The slow wet-chemical etching rate enables us to gain control of the lens aspect-ratio and the vertical position with respect to the quantum dot, allowing us to engineer the far field shape to better match the acceptance profile of single-mode fibers. Maximum light enhancement values of around 10 to 16 could be achieved for collection numerical apertures from 0.6 to 0.2, respectively. The current results constitute an important step forward in transferring state-of-the-art performances achieved in the near-infrared regime to the key wavelengths for long distance fiber communication.}, author = {Sartison, Marc and Engel, Lena and Kolatschek, Sascha and Olbrich, Fabian and Nawrath, Cornelius and Hepp, Stefan and Jetter, Michael and Michler, Peter and Portalupi, Simone Luca}, booktitle = {Applied Physics Letters}, comment = {doi: 10.1063/1.5038271}, doi = {10.1063/1.5038271}, issn = {00036951}, journal = {Appl. Phys. Lett.}, month = {07}, number = 3, pages = {032103--}, privnote = {doi: 10.1063/1.5038271}, publisher = {American Institute of Physics}, title = {Deterministic integration and optical characterization of telecom O-band quantum dots embedded into wet-chemically etched Gaussian-shaped microlenses}, url = {https://doi.org/10.1063/1.5038271}, volume = 113, year = 2018 }
  Link
  https://doi.org/10.1063/1.5038271
2017
1. Kahle, H., Mateo, C. M., Bek, R., Jetter, M., & Brauch, U. (2017). Heat sink sandwich extends wavelength for semiconductor membrane laser. LASER FOCUS WORLD, 53(6), Article 6.
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  @article{kahle2017sandwich, affiliation = {Brauch, U (Reprint Author), Univ Stuttgart, Stuttgart Res Ctr Photon Engn SCoPE, Stuttgart, Germany. Kahle, Hermann; Mateo, Cherry May; Bek, Roman; Jetter, Michael; Brauch, Uwe, Univ Stuttgart, Stuttgart Res Ctr Photon Engn SCoPE, Stuttgart, Germany.}, author = {Kahle, Hermann and Mateo, Cherry May and Bek, Roman and Jetter, Michael and Brauch, Uwe}, da = {2018-05-28}, issn = {1043-8092}, journal = {LASER FOCUS WORLD}, language = {English}, month = {06}, number = 6, orcid-numbers = {Jetter, Michael/0000-0002-1311-6550}, pages = {70-73}, publisher = {PENNWELL PUBL CO}, research-areas = {Optics}, title = {Heat sink sandwich extends wavelength for semiconductor membrane laser}, type = {Article}, unique-id = {ISI:000404326700022}, volume = 53, year = 2017 }
2. Bek, R., Grossmann, M., Kahle, H., Koch, M., Rahimi-Iman, A., Jetter, M., & Michler, P. (2017). Self-mode-locked AlGaInP-VECSEL. APPLIED PHYSICS LETTERS, 111(18), Article 18. https://doi.org/10.1063/1.5010689
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  @article{bek2017selfmodelocked, affiliation = {Bek, R (Reprint Author), Univ Stuttgart, Inst Halbleiteropt \& Funkt Grenzflachen, Ctr Integrated Quantum Sci \& Technol IQ, Allmandring 3, D-70569 Stuttgart, Germany. Bek, R (Reprint Author), Univ Stuttgart, Res Ctr SCoPE, Allmandring 3, D-70569 Stuttgart, Germany. Bek, R.; Grossmann, M.; Kahle, H.; Jetter, M.; Michler, P., Univ Stuttgart, Inst Halbleiteropt \& Funkt Grenzflachen, Ctr Integrated Quantum Sci \& Technol IQ, Allmandring 3, D-70569 Stuttgart, Germany. Bek, R.; Grossmann, M.; Kahle, H.; Jetter, M.; Michler, P., Univ Stuttgart, Res Ctr SCoPE, Allmandring 3, D-70569 Stuttgart, Germany. Koch, M.; Rahimi-Iman, A., Philipps Univ Marburg, Dept Phys, Renthof 5, D-35032 Marburg, Germany. Koch, M.; Rahimi-Iman, A., Philipps Univ Marburg, Mat Sci Ctr, Renthof 5, D-35032 Marburg, Germany.}, article-number = {182105}, author = {Bek, Roman and Grossmann, Marius and Kahle, Holger and Koch, M. and Rahimi-Iman, A. and Jetter, Michael and Michler, Peter}, da = {2018-01-12}, doi = {10.1063/1.5010689}, eissn = {1077-3118}, issn = {0003-6951}, journal = {APPLIED PHYSICS LETTERS}, language = {English}, month = {10}, number = 18, orcid-numbers = {Kahle, Hermann/0000-0002-5315-704X Jetter, Michael/0000-0002-1311-6550}, publisher = {AMER INST PHYSICS}, research-areas = {Physics}, title = {Self-mode-locked AlGaInP-VECSEL}, type = {Article}, unique-id = {ISI:000414158500011}, volume = 111, year = 2017 }
3. Mirkhanov, S., Quarterman, A. H., Kahle, H., Bek, R., Pecoroni, R., Smyth, C. J. C., Vollmer, S., Swift, S., Michler, P., Jetter, M., & Wilcox, K. G. (2017). DBR-free semiconductor disc laser on SiC heatspreader emitting 10.1 W at 1007 nm. Electronics Letters, 53(23), Article 23. https://doi.org/10.1049/el.2017.2689
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  @article{Mirkhanov_2017, author = {Mirkhanov, S. and Quarterman, A.H. and Kahle, H. and Bek, R. and Pecoroni, R. and Smyth, C.J.C. and Vollmer, S. and Swift, S. and Michler, P. and Jetter, M. and Wilcox, K.G.}, doi = {10.1049/el.2017.2689}, journal = { Electronics Letters}, month = {11}, number = 23, pages = {1537--1539}, publisher = {Institution of Engineering and Technology ({IET})}, title = {DBR-free semiconductor disc laser on SiC heatspreader emitting 10.1 W at 1007 nm }, url = {https://doi.org/10.1049%2Fel.2017.2689}, volume = 53, year = 2017 }
  Link
  https://doi.org/10.1049%2Fel.2017.2689
4. Kahle, H., Mateo, C. M., Brauch, U., Bek, R., Jetter, M., Graf, T., & Michler, P. (2017). Novel semiconductor membrane external-cavity surface-emitting laser. SPIE Newsroom. https://doi.org/10.1117/2.1201703.006864
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  @article{noauthororeditor, abstract = {An optically pumped device features a semiconductor membrane sandwiched between diamond heat spreaders to maximize heat dissipation from the active region.}, author = {Kahle, Herman and Mateo, Cherry May and Brauch, Uwe and Bek, Roman and Jetter, Michael and Graf, Thomas and Michler, Peter}, doi = {10.1117/2.1201703.006864}, journal = {SPIE Newsroom }, title = {Novel semiconductor membrane external-cavity surface-emitting laser}, year = 2017 }
2016
1. Kahle, H., Mateo, C. M. N., Brauch, U., Bek, R., Schwarzbäck, T., Jetter, M., Graf, T., & Michler, P. (2016). Gain chip design, power scaling and intra-cavity frequency doubling with LBO of optically pumped red-emitting AlGaInP-VECSELs. /brokenurl#NULL
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  BibTeX
  @proceedings{noauthororeditor, author = {Kahle, Hermann and Mateo, Cherry M. N. and Brauch, Uwe and Bek, Roman and Schwarzbäck, Thomas and Jetter, Michael and Graf, Thomas and Michler, Peter}, title = {Gain chip design, power scaling and intra-cavity frequency doubling with LBO of optically pumped red-emitting AlGaInP-VECSELs }, url = {/brokenurl#NULL}, year = 2016 }
  Link
  /brokenurl#NULL
2. Mateo, C. M. N., Brauch, U., Kahle, H., Bek, R., Schwarzbäck, T., Jetter, M., Ahmed, M. A., Michler, P., & Graf, T. (2016). Efficiency and power scaling of in-well and multi-pass pumped AlGaInP-VECSELs. /brokenurl#NULL
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  BibTeX
  @proceedings{noauthororeditor, author = {Mateo, Cherry M. N. and Brauch, Uwe and Kahle, Hermann and Bek, Roman and Schwarzbäck, Thomas and Jetter, Michael and Ahmed, Marwan Abdou and Michler, Peter and Graf, Thomas}, title = {Efficiency and power scaling of in-well and multi-pass pumped AlGaInP-VECSELs}, url = {/brokenurl#NULL}, year = 2016 }
  Link
  /brokenurl#NULL
3. Hargart, F., Roy-Choudhury, K., John, T., Portalupi, S. L., Schneider, C., Höfling, S., Kamp, M., Hughes, S., & Michler, P. (2016). Probing different regimes of strong field light–matter interaction with semiconductor quantum dots and few cavity photons. New Journal of Physics, 18(12), Article 12. http://stacks.iop.org/1367-2630/18/i=12/a=123031
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  BibTeX
  @article{hargart2016probing, abstract = {In this work we present an extensive experimental and theoretical investigation of different regimes of strong field light–matter interaction for cavity-driven quantum dot (QD) cavity systems. The electric field enhancement inside a high-Q micropillar cavity facilitates exceptionally strong interaction with few cavity photons, enabling the simultaneous investigation for a wide range of QD-laser detuning. In case of a resonant drive, the formation of dressed states and a Mollow triplet sideband splitting of up to 45 μ eV is measured for a mean cavity photon number ##IMG## [http://ej.iop.org/images/1367-2630/18/12/123031/njpaa5198ieqn2.gif] {$\langle {n}_{c}\rangle \leqslant 1$} . In the asymptotic limit of the linear AC Stark effect we systematically investigate the power and detuning dependence of more than 400 QDs. Some QD-cavity systems exhibit an unexpected anomalous Stark shift, which can be explained by an extended dressed 4-level QD model. We provide a detailed analysis of the QD-cavity systems properties enabling this novel effect. The experimental results are successfully reproduced using a polaron master equation approach for the QD-cavity system, which includes the driving laser field, exciton-cavity and exciton-phonon interactions.}, author = {Hargart, F and Roy-Choudhury, K and John, T and Portalupi, S L and Schneider, C and Höfling, S and Kamp, M and Hughes, S and Michler, P}, journal = {New Journal of Physics}, number = 12, pages = 123031, title = {Probing different regimes of strong field light–matter interaction with semiconductor quantum dots and few cavity photons}, url = {http://stacks.iop.org/1367-2630/18/i=12/a=123031}, volume = 18, year = 2016 }
  Link
  http://stacks.iop.org/1367-2630/18/i=12/a=123031
4. Kahle, H. P., Mateo, C. M. N., Brauch, U., Tatar-Mathes, P., Bek, R., Jetter, M., Graf, T., & Michler, P. (2016). Semiconductor membrane external-cavity surface-emitting laser (MECSEL). Optica, 3(12), Article 12.
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  BibTeX
  @article{Kahle.2016.Semiconductor, author = {Kahle, Hermann Paul and Mateo, Cherry May N. and Brauch, Uwe and Tatar-Mathes, Philipp and Bek, Roman and Jetter, Michael and Graf, Thomas and Michler, Peter}, journal = {Optica}, number = 12, pages = 1506, title = {Semiconductor membrane external-cavity surface-emitting laser (MECSEL)}, volume = 3, year = 2016 }
2015
1. Baumgaertner, S., Kahle, H., Bek, R., Schwarzbaeck, T., Jetter, M., & Michler, P. (2015). Comparison of AlGaInP-VECSEL gain structures. JOURNAL OF CRYSTAL GROWTH, 414, 219–222. https://doi.org/10.1016/j.jcrysgro.2014.10.016
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  @article{baumgaertner2015comparison, affiliation = {Baumgartner, S (Reprint Author), Univ Stuttgart, Inst Halbleiteropt \& Funkt Grenzflache, Allmandring 3, D-70569 Stuttgart, Germany. Baumgaertner, Stefan, Univ Stuttgart, Inst Halbleiteropt \& Funkt Grenzflache, D-70569 Stuttgart, Germany. Univ Stuttgart, Res Ctr SCoPE, D-70569 Stuttgart, Germany.}, author = {Baumgaertner, Stefan and Kahle, Hermann and Bek, Roman and Schwarzbaeck, Thomas and Jetter, Michael and Michler, Peter}, doi = {10.1016/j.jcrysgro.2014.10.016}, eissn = {1873-5002}, issn = {0022-0248}, journal = {JOURNAL OF CRYSTAL GROWTH}, language = {English}, month = {03}, orcid-numbers = {Jetter, Michael/0000-0002-1311-6550}, pages = {219-222}, publisher = {ELSEVIER SCIENCE BV}, research-areas = {Crystallography; Materials Science; Physics}, researcherid-numbers = {Jetter, Michael/I-8270-2012}, title = {Comparison of AlGaInP-VECSEL gain structures}, type = {Article}, unique-id = {ISI:000349602900041}, volume = 414, year = 2015 }
2. Stadler, M., Kahle, H., Bek, R., Huang, Z., Jetter, M., & Michler, P. (2015). Poster:Towards AlGaInP-based electrically-pumped VECSELs emitting in the red spectral range.
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  BibTeX
  @conference{noauthororeditor, author = {Stadler, M. and Kahle, H. and Bek, R. and Huang, Z. and Jetter, M. and Michler, P.}, title = {Poster:Towards AlGaInP-based electrically-pumped VECSELs emitting in the red spectral range }, year = 2015 }
3. Bek, R., Baumgaertner, S., Sauter, F., Kahle, H., Schwarzbaeck, T., Jetter, M., & Michler, P. (2015). Intra-cavity frequency-doubled mode-locked semiconductor disk laser at 325 nm. OPTICS EXPRESS, 23(15), Article 15. https://doi.org/10.1364/OE.23.019947
  - BibTeX
  BibTeX
  @article{bek2015intracavity, affiliation = {Bek, R (Reprint Author), Univ Stuttgart, Inst Halbleiteropt \& Funkt Grenzflachen, Allmandring 3, D-70569 Stuttgart, Germany. Bek, Roman; Baumgaertner, Stefan; Sauter, Fabian; Kahle, Hermann; Schwarzbaeck, Thomas; Jetter, Michael; Michler, Peter, Univ Stuttgart, Inst Halbleiteropt \& Funkt Grenzflachen, D-70569 Stuttgart, Germany. Bek, Roman; Baumgaertner, Stefan; Sauter, Fabian; Kahle, Hermann; Schwarzbaeck, Thomas; Jetter, Michael; Michler, Peter, Univ Stuttgart, Res Ctr SCoPE, D-70569 Stuttgart, Germany. Schwarzbaeck, Thomas, TRUMPF Lasersyst Semicond Mfg GmbH, Div Opt Dev, D-71245 Ditzingen, Germany.}, author = {Bek, Roman and Baumgaertner, Stefan and Sauter, Fabian and Kahle, Hermann and Schwarzbaeck, Thomas and Jetter, Michael and Michler, Peter}, doi = {10.1364/OE.23.019947}, issn = {1094-4087}, journal = {OPTICS EXPRESS}, language = {English}, month = {07}, number = 15, pages = {19947-19953}, publisher = {OPTICAL SOC AMER}, research-areas = {Optics}, title = {Intra-cavity frequency-doubled mode-locked semiconductor disk laser at 325 nm}, type = {Article}, unique-id = {ISI:000361035300134}, volume = 23, year = 2015 }
4. Kahle, H., Baumgärtner, S., Sauter, F., Bek, R., Schwarzbäck, T., Jetter, M., & and P. Michler. (2015). Talk:High-power (>400 mW) laser emission at 332 nm of frequency-doubled, optically pumped AlGaInP disk laser with an optimized quantum well structure.
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  @conference{noauthororeditor, author = {Kahle, H. and Baumgärtner, S. and Sauter, F. and Bek, R. and Schwarzbäck, T. and Jetter, M. and and P. Michler}, title = {Talk:High-power (>400 mW) laser emission at 332 nm of frequency-doubled, optically pumped AlGaInP disk laser with an optimized quantum well structure}, year = 2015 }
5. Kahle, H., Mateo, C. M. N., Jäger, M., Weinspach, K., Baumgärtner, S., Brauch, U., Bek, R., Schwarzbäck, T., Jetter, M., Graf, T., & Michler, P. (2015). Degradation studies and pump optimization of optically pumped red-emitting AlGaInP-VECSELs. /brokenurl#NULL
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  - Link
  BibTeX
  @proceedings{noauthororeditor, author = {Kahle, Hermann and Mateo, Cherry M. N. and Jäger, Maren and Weinspach, Karoline and Baumgärtner, Stefan and Brauch, Uwe and Bek, Roman and Schwarzbäck, Thomas and Jetter, Michael and Graf, Thomas and Michler, Peter}, title = {Degradation studies and pump optimization of optically pumped red-emitting AlGaInP-VECSELs }, url = {/brokenurl#NULL}, year = 2015 }
  Link
  /brokenurl#NULL
6. Bek, R., Kersteen, G., Kahle, H., Schwarzbäck, T., Jetter, M., & Michler, P. (2015). Talk:Quantum dot based mode-locked AlGaInP-VECSEL.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Bek, R. and Kersteen, G. and Kahle, H. and Schwarzbäck, T. and Jetter, M. and Michler, P.}, title = {Talk:Quantum dot based mode-locked AlGaInP-VECSEL}, year = 2015 }
7. Bek, R., Kersteen, G., Kahle, H., Schwarzbäck, T., Jetter, M., & Michler, P. (2015). Quantum dot based mode-locked AlGaInP-VECSEL. /brokenurl#NULL
  - BibTeX
  - Link
  BibTeX
  @proceedings{noauthororeditor, author = {Bek, Roman and Kersteen, Grizelda and Kahle, Hermann and Schwarzbäck, Thomas and Jetter, Michael and Michler, Peter}, title = {Quantum dot based mode-locked AlGaInP-VECSEL}, url = {/brokenurl#NULL}, year = 2015 }
  Link
  /brokenurl#NULL
2014
1. Bek, R., Kersteen, G., Kahle, H., Schwarzbäck, T., Jetter, M., & Michler, P. (2014). All quantum dot mode-locked semiconductor disk laser emitting at 655 nm. Applied Physics Letters, 105(082107), Article 082107. https://doi.org/10.1063/1.4894182
  - BibTeX
  BibTeX
  @article{noauthororeditor, author = {Bek, Roman and Kersteen, Griselda and Kahle, Hermann and Schwarzbäck, Thomas and Jetter, Michael and Michler, Peter}, doi = {https://doi.org/10.1063/1.4894182}, journal = {Applied Physics Letters}, number = {082107 }, title = {All quantum dot mode-locked semiconductor disk laser emitting at 655 nm}, volume = 105, year = 2014 }
2. Baumgärtner, S., Kahle, H., Bek, R., Schwarzbäck, T., Jetter, M., & Michler, P. (2014). Poster:Comparison of AlGaInP-VECSEL gain structures.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Baumgärtner, S. and Kahle, H. and Bek, R. and Schwarzbäck, T. and Jetter, M. and Michler, P.}, title = {Poster:Comparison of AlGaInP-VECSEL gain structures}, year = 2014 }
3. Baumgärtner, S., Kahle, H., Bek, R., Schwarzbäck, T., Jetter, M., & Michler, P. (2014). Talk:Gainstrukturen für AlGaInP-basierte Halbleiterscheibenlaser im roten Spektralbereich.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Baumgärtner, S. and Kahle, H. and Bek, R. and Schwarzbäck, T. and Jetter, M. and Michler, P.}, title = {Talk:Gainstrukturen für AlGaInP-basierte Halbleiterscheibenlaser im roten Spektralbereich }, year = 2014 }
4. Kahle, H., Bek, R., Heldmaier, M., Schwarzbäck, T., Jetter, M., & Michler, P. (2014). High optical output power in the UVA range of a frequency-doubled, strain-compensated AlGaInP-VECSEL. Applied Physics Express, 7(092705), Article 092705. http://dx.doi.org/10.7567/APEX.7.092705
  - BibTeX
  BibTeX
  @article{noauthororeditor, author = {Kahle, Hermann and Bek, Roman and Heldmaier, Matthias and Schwarzbäck, Thomas and Jetter, Michael and Michler, Peter}, doi = {http://dx.doi.org/10.7567/APEX.7.092705}, journal = {Applied Physics Express}, number = 092705, title = {High optical output power in the UVA range of a frequency-doubled, strain-compensated AlGaInP-VECSEL}, volume = 7, year = 2014 }
5. Bek, R., Daghestani, N. S., Kahle, H., Schwarzbäck, T., Jetter, M., Cataluna, M. A., & Michler, P. (2014). Femtosecond mode-locked red AlGaInP-VECSEL. http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=1840291
  - BibTeX
  - Link
  BibTeX
  @proceedings{noauthororeditor, author = {Bek, Roman and Daghestani, Nart S. and Kahle, Hermann and Schwarzbäck, Thomas and Jetter, Michael and Cataluna, Maria Ana and Michler, Peter}, title = {Femtosecond mode-locked red AlGaInP-VECSEL }, url = {http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=1840291}, year = 2014 }
  Link
  http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=1840291
2013
1. Schwarzbäck, T., Bek, R., Kahle, H., Jetter, M., & and Peter Michler. (2013). Talk: SESAM mode-locked red AlGaInP semiconductor disk laser emitting at 665 nm.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Schwarzbäck, Thomas and Bek, Roman and Kahle, Hermann and Jetter, Michael and and Peter Michler}, title = {Talk: SESAM mode-locked red AlGaInP semiconductor disk laser emitting at 665 nm }, year = 2013 }
2. Koroknay, E., Rengstl, U., Bommer, M., Jetter, M., & Michler, P. (2013). Site-controlled growth of InP/GaInP islands on periodic hole patterns in GaAs substrates produced by microsphere photolithography. Journal of Crystal Growth, 370, 146–149. https://doi.org/10.1016/j.jcrysgro.2012.09.058
  - BibTeX
  - Link
  BibTeX
  @article{KOROKNAY2013146, abstract = {We present microsphere photolithography in combination with wet chemical etching as a fast and low-cost method to produce regular hole arrays in a (100) GaAs surface, which are suitable for controlled nucleation of self-organized InP islands in a metal–organic vapor-phase epitaxy (MOVPE) system. A hexagonal close-packed monolayer of microspheres is used as an array of microlenses to focus UV-light on UV-sensitive photoresist. In this way, regular arrays of holes with 2μm spacing can be realized in the photoresist with controllable feature size in the sub-μm range, which are transferred to a GaAs buffer, using an isotropic etchant. These templates are used to study the site-controlled nucleation of InP islands on a Ga0.51In0.49P barrier. For this purpose the subsequent overgrowth of the templates with a GaAs buffer layer and the GaInP barrier is investigated previous to the additional deposition of the InP. The template quality is monitored during structuring and overgrowth experiments using atomic force microscopy (AFM). Preferred nucleation of InP islands inside the almost filled holes can be observed for uncapped samples. The correlation between the initial patterning and the optical signal of the InP islands is investigated by micro-photoluminescence (micro-PL) measurements. We observe site-controlled nucleation of large, but optically active, InP islands on these templates.}, author = {Koroknay, E. and Rengstl, U. and Bommer, M. and Jetter, M. and Michler, P.}, doi = {https://doi.org/10.1016/j.jcrysgro.2012.09.058}, issn = {0022-0248}, journal = {Journal of Crystal Growth}, note = {16th International Conference on Metalorganic Vapor Phase Epitaxy}, pages = {146 - 149}, title = {Site-controlled growth of InP/GaInP islands on periodic hole patterns in GaAs substrates produced by microsphere photolithography}, url = {http://www.sciencedirect.com/science/article/pii/S0022024812008512}, volume = 370, year = 2013 }
  Link
  http://www.sciencedirect.com/science/article/pii/S0022024812008512
3. Bek, R., Kahle, H., Schwarzbäck, T., Jetter, M., & Michler, P. (2013). Mode-locked red-emitting semiconductor disk laser with sub-250 fs pulses. Applied Physics Letters, 103(242101), Article 242101. https://doi.org/10.1063/1.4835855
  - BibTeX
  BibTeX
  @article{noauthororeditor, author = {Bek, Roman and Kahle, Hermann and Schwarzbäck, Thomas and Jetter, Michael and Michler, Peter}, doi = {https://doi.org/10.1063/1.4835855}, journal = {Applied Physics Letters}, number = 242101, title = {Mode-locked red-emitting semiconductor disk laser with sub-250 fs pulses}, volume = 103, year = 2013 }
4. Schwarzbäck, T., Bek, R., Hargart, F., Kessler, C. A., Kahle, H., Koroknay, E., Jetter, M., & Michler, P. (2013). Talk:Red quantum dot based semiconductor disk laser.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Schwarzbäck, T. and Bek, R. and Hargart, F. and Kessler, C. A. and Kahle, H. and Koroknay, E. and Jetter, M. and Michler, P.}, title = {Talk:Red quantum dot based semiconductor disk laser }, year = 2013 }
5. Schwarzbäck, T., Bek, R., Hargart, F., Kessler, C. A., Kahle, H., Koroknay, E., Jetter, M., & Michler, P. (2013). Talk:InP quantum dot based semiconductor disk laser.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Schwarzbäck, T. and Bek, R. and Hargart, F. and Kessler, C. A. and Kahle, H. and Koroknay, E. and Jetter, M. and Michler, P.}, title = {Talk:InP quantum dot based semiconductor disk laser}, year = 2013 }
6. Kahle, H., Bek, R., Rengstl, U., Schwarzbäck, T., Jetter, M., & Michler, P. (2013). Strain compensated 10x2 quantum well AlGaInP-VECSEL emitting below 660 nm frequency doubled for UV output up to 260 mW. /brokenurl#NULL
  - BibTeX
  - Link
  BibTeX
  @proceedings{noauthororeditor, author = {Kahle, Hermann and Bek, Roman and Rengstl, Ulrich and Schwarzbäck, Thomas and Jetter, Michael and Michler, Peter}, title = {Strain compensated 10x2 quantum well AlGaInP-VECSEL emitting below 660 nm frequency doubled for UV output up to 260 mW}, url = {/brokenurl#NULL}, year = 2013 }
  Link
  /brokenurl#NULL
7. Schwarzbäck, T., Bek, R., Hargart, F., Kessler, C. A., Kahle, H., Koroknay, E., Jetter, M., & Michler, P. (2013). InP quantum dots used as gain media for a red emitting VECSEL. /brokenurl#NULL
  - BibTeX
  - Link
  BibTeX
  @proceedings{noauthororeditor, author = {Schwarzbäck, T. and Bek, R. and Hargart, F. and Kessler, C. A. and Kahle, H. and Koroknay, E. and Jetter, M. and Michler, P.}, title = {InP quantum dots used as gain media for a red emitting VECSEL}, url = {/brokenurl#NULL}, year = 2013 }
  Link
  /brokenurl#NULL
8. Schwarzbäck, T., Bek, R., Kahle, H., Rengstl, U., Hargart, F., Kessler, C. A., Koroknay, E., Jetter, M., & and P. Michler. (2013). Talk:Epitaxy of AlGaInP based semiconductor disk lasers: wells, dots, frequency doubling and mode locking.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Schwarzbäck, T. and Bek, R. and Kahle, H. and Rengstl, U. and Hargart, F. and Kessler, C. A. and Koroknay, E. and Jetter, M. and and P. Michler}, title = {Talk:Epitaxy of AlGaInP based semiconductor disk lasers: wells, dots, frequency doubling and mode locking}, year = 2013 }
9. Schwarzbäck, T., Rengstl, U., Niederbracht, H., Bek, R., Kahle, H., Jetter, M., & and Peter Michler. (2013). Talk:Thermisches Management einer QW-Membran im Hinblick auf Leistungsskalierung roter Halbleiterscheibenlaser.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Schwarzbäck, Thomas and Rengstl, Ulrich and Niederbracht, Hendrik and Bek, Roman and Kahle, Hermann and Jetter, Michael and and Peter Michler}, title = {Talk:Thermisches Management einer QW-Membran im Hinblick auf Leistungsskalierung roter Halbleiterscheibenlaser}, year = 2013 }
10. Schwarzbäck, T., Bek, R., Hargart, F., Kessler, C. A., Kahle, H., Koroknay, E., Jetter, M., & Michler, P. (2013). High-power InP quantum dot based semiconductor disk laser exceeding 1.3 W. Applied Physics Letters, 102(092101), Article 092101. https://doi.org/10.1063/1.4793299
  - BibTeX
  BibTeX
  @article{noauthororeditor, author = {Schwarzbäck, Thomas and Bek, Roman and Hargart, Fabian and Kessler, Christian A. and Kahle, Hermann and Koroknay, Elisabeth and Jetter, Michael and Michler, Peter}, doi = {https://doi.org/10.1063/1.4793299}, journal = {Applied Physics Letters}, number = { 092101}, title = {High-power InP quantum dot based semiconductor disk laser exceeding 1.3 W }, volume = 102, year = 2013 }
11. Schwarzbäck, T., Kahle, H., Jetter, M., & Michler, P. (2013). Strain compensation techniques for red AlGaInP-VECSELs: Performance comparison of epitaxial designs. Journal of Crystal Growth, 370, 208–211. https://doi.org/10.1016/j.jcrysgro.2012.09.051
  - BibTeX
  - Link
  BibTeX
  @article{SCHWARZBACK2013208, abstract = {We present a strain-compensation design for non-resonantly pumped vertical external cavity surface-emitting lasers for emission in the red spectral range around 665nm. Here, the VECSEL chip is based on a metal-organic vapor-phase epitaxy grown (GaxIn1−x)0.5P0.5/[(AlxGa1−x)yIn 1−y]0.5P0.5 multi-quantum-well structure with 20 compressively strained quantum wells. By introducing tensile strained quaternary barriers and cladding layers in a 5×4 QW design, we could compensate for the compressive strain introduced by the quantum wells. Photoluminenscence measurements of structures with different numbers of quantum well packages reveal a more homogenous quantum well growth due to the strain-compensation technique. Furthermore, with the strain compensation technique, the output power could be increased over 30% compared to our conventional structures.}, author = {Schwarzbäck, Thomas and Kahle, Hermann and Jetter, Michael and Michler, Peter}, doi = {https://doi.org/10.1016/j.jcrysgro.2012.09.051}, issn = {0022-0248}, journal = {Journal of Crystal Growth}, note = {16th International Conference on Metalorganic Vapor Phase Epitaxy}, pages = {208 - 211}, title = {Strain compensation techniques for red AlGaInP-VECSELs: Performance comparison of epitaxial designs}, url = {http://www.sciencedirect.com/science/article/pii/S0022024812008421}, volume = 370, year = 2013 }
  Link
  http://www.sciencedirect.com/science/article/pii/S0022024812008421
2012
1. Schwarzbäck, T., Kahle, H., Bek, R., Jetter, M., & and Peter Michler. (2012). Talk:Frequency doubled AlGaInP-VECSEL with high output power at 331 nm and a large wavelength tuning range in the UV.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Schwarzbäck, Thomas and Kahle, Hermann and Bek, Roman and Jetter, Michael and and Peter Michler}, title = {Talk:Frequency doubled AlGaInP-VECSEL with high output power at 331 nm and a large wavelength tuning range in the UV}, year = 2012 }
2. Schwarzbäck, T., Bek, R., Hargart, F., Kessler, C. A., Kahle, H., Koroknay, E., Jetter, M., & Michler, P. (2012). Talk:InP quantenpunktbasierter Halbleiterscheibenlaser.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Schwarzbäck, T. and Bek, R. and Hargart, F. and Kessler, C. A. and Kahle, H. and Koroknay, E. and Jetter, M. and Michler, P.}, title = {Talk:InP quantenpunktbasierter Halbleiterscheibenlaser}, year = 2012 }
2011
1. Wagner, J., Niederbracht, H., Schulz, W.-M., M. Eichfelder, M. J., & and P. Michler. (2011). Talk:Herstellung eines bei 632 nm emittierenden elektrisch gepumpten InP/AlGaInP Quantenpunkt-Kantenemitters.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Wagner, J. and Niederbracht, H. and Schulz, W.-M. and M. Eichfelder, M. Jetter and and P. Michler}, title = {Talk:Herstellung eines bei 632 nm emittierenden elektrisch gepumpten InP/AlGaInP Quantenpunkt-Kantenemitters}, year = 2011 }
2. Plumhof, J. D., KrÃ¡pek, V., Ding, F., Jöns, K. D., Hafenbrak, R., KlenovskÃ½, P., Herklotz, A., Dörr, K., Michler, P., Rastelli, A., & and O. G. Schmidt. (2011). Strain-induced anticrossing of bright exciton levels in single self-assembled GaAs/Al(x)Ga(1-x)As and In(x)Ga(1-x)As/GaAs quantum dots. http://link.aps.org/doi/10.1103/PhysRevB.83.121302
  - BibTeX
  - Link
  BibTeX
  @article{noauthororeditor, author = {Plumhof, J. D. and KrÃ¡pek, V. and Ding, F. and Jöns, K. D. and Hafenbrak, R. and KlenovskÃ½, P. and Herklotz, A. and Dörr, K. and Michler, P. and Rastelli, A. and and O. G. Schmidt}, title = {Strain-induced anticrossing of bright exciton levels in single self-assembled GaAs/Al(x)Ga(1-x)As and In(x)Ga(1-x)As/GaAs quantum dots}, url = {http://link.aps.org/doi/10.1103/PhysRevB.83.121302}, year = 2011 }
  Link
  http://link.aps.org/doi/10.1103/PhysRevB.83.121302
3. Schwarzbaeck, T., Eichfelder, M., Schulz, W.-M., Rossbach, R., Jetter, M., & Michler, P. (2011). Short wavelength red-emitting AlGaInP-VECSEL exceeds 1.2 W continuous-wave output power. Applied Physics B, 102(4), Article 4. https://doi.org/10.1007/s00340-010-4213-5
  - BibTeX
  - Link
  BibTeX
  @article{Schwarzbäck2011, abstract = {We present a vertical external cavity surface-emitting laser system based on a multi-quantum-well structure with 20 compressively strained GaInP quantum wells for an operation wavelength of around 665 nm with a monolithic integrated distributed Bragg reflector. With the help of an intra-cavity diamond heatspreader the laser operates in continuous-wave mode. Operation with a TEM00 Gaussian beam profile and a beam propagation factor of M2≤1.05 is shown as well as a high resolution spectrum of the laser line, which shows the etalon effect of the diamond. The laser can be operated at a maximum output power exceeding 1.2 W with a slope efficiency of $\eta$diff=18{\%}. At maximum output power the wavelength of the laser resonance is at 670 nm, which is shortest reported until now at powers exceeding 1 W. By rotating a birefringent filter in an extended folded cavity arrangement a wavelength tuning of 21 nm was attained.}, author = {Schwarzbaeck, T. and Eichfelder, M. and Schulz, W.-M. and Rossbach, R. and Jetter, M. and Michler, P.}, day = 01, doi = {10.1007/s00340-010-4213-5}, issn = {1432-0649}, journal = {Applied Physics B}, month = {03}, number = 4, pages = {789--794}, title = {Short wavelength red-emitting AlGaInP-VECSEL exceeds 1.2 W continuous-wave output power}, url = {https://doi.org/10.1007/s00340-010-4213-5}, volume = 102, year = 2011 }
  Link
  https://doi.org/10.1007/s00340-010-4213-5
2010
1. Wiesner, M., Etter, M., Schulz, W.-M., Richter, D., Roßbach, R., Jetter, M., & Michler, P. (2010). Talk:Reduzierung der Versetzungsdichte bei der Heteroepitaxie von III/V auf Si durch InAs-Quantenpunktschichten.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Wiesner, M. and Etter, M. and Schulz, W.-M. and Richter, D. and Roßbach, R. and Jetter, M. and Michler, P.}, title = {Talk:Reduzierung der Versetzungsdichte bei der Heteroepitaxie von III/V auf Si durch InAs-Quantenpunktschichten}, year = 2010 }
2009
1. Schulz, W.-M., Eichfelder, M., Roßbach, R., Jetter, M., & und Peter Michler. (2009). Talk:Elektrisch gepumpter Quantenpunkt-Kantenemitter bei 638 nm.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Schulz, Wolfgang-Michael and Eichfelder, Marcus and Roßbach, Robert and Jetter, Michael and und Peter Michler}, title = {Talk:Elektrisch gepumpter Quantenpunkt-Kantenemitter bei 638 nm}, year = 2009 }
2008
1. Eichfelder, M., W.-M.Schulz, Roßbach, R., Jetter, M., & and P. Michler. (2008). Rückätzen bei der Verwendung von CBr4 als Dotierstoff in As-haltigen Bragg Reflektoren für VCSEL.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Eichfelder, M. and W.-M.Schulz and Roßbach, R. and Jetter, M. and and P. Michler}, title = {Rückätzen bei der Verwendung von CBr4 als Dotierstoff in As-haltigen Bragg Reflektoren für VCSEL}, year = 2008 }
2007
1. Reischle, M., Beirne, G. J., Roßbach, R., Jetter, M., Schweizer, H., & and P. Michler. (2007). Optical investigations of single pairs of vertically stacked asymmetric InP/GaInP quantum dots. /brokenurl#NULL
  - BibTeX
  - Link
  BibTeX
  @article{noauthororeditor, author = {Reischle, M. and Beirne, G. J. and Roßbach, R. and Jetter, M. and Schweizer, H. and and P. Michler}, title = {Optical investigations of single pairs of vertically stacked asymmetric InP/GaInP quantum dots}, url = {/brokenurl#NULL}, year = 2007 }
  Link
  /brokenurl#NULL
2006
1. Hermannstädter, C., Beirne, G. J., Wang, L., Rastelli, A., Schmidt, O. G., & and P. Michler. (2006). Time-Resolved Optical Spectroscopy of Tunnel-Coupled Lateral Quantum Dot Molecules. /brokenurl#NULL
  - BibTeX
  - Link
  BibTeX
  @article{noauthororeditor, author = {Hermannstädter, C. and Beirne, G. J. and Wang, L. and Rastelli, A. and Schmidt, O. G. and and P. Michler}, title = {Time-Resolved Optical Spectroscopy of Tunnel-Coupled Lateral Quantum Dot Molecules}, url = {/brokenurl#NULL}, year = 2006 }
  Link
  /brokenurl#NULL
2. Bolse, W. (2006). Instabilität und Selbstorganisation bei der Bestrahlung von Schichtpaketen mit hochenergetischen Ionen.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Bolse, W.}, title = {Instabilität und Selbstorganisation bei der Bestrahlung von Schichtpaketen mit hochenergetischen Ionen}, year = 2006 }
2004
1. Jetter, M., & Roßbach, R. (2004). Talk:Technologietransfer bei InPQuantenpunkten.
  - BibTeX
  BibTeX
  @conference{noauthororeditor, author = {Jetter, Michael and Roßbach, Robert}, title = {Talk:Technologietransfer bei InPQuantenpunkten}, year = 2004 }
2001
1. Michler, P., Kiraz, A., Becher, C., Schoenfeld, W. V., Petroff, P. M., Zhang, L., Hu, E., & and A. Imamoglu. (2001). A Quantum Dot Single Photon Source. http://www.sciencemag.org/content/290/5500/2282.abstract
  - BibTeX
  - Link
  BibTeX
  @proceedings{noauthororeditor, author = {Michler, P. and Kiraz, A. and Becher, C. and Schoenfeld, W. V. and Petroff, P. M. and Zhang, Lidong and Hu, E. and and A. Imamoglu}, title = {A Quantum Dot Single Photon Source}, url = {http://www.sciencemag.org/content/290/5500/2282.abstract}, year = 2001 }
  Link
  http://www.sciencemag.org/content/290/5500/2282.abstract
1999
1. Aichmayer, G., Jetter, M., Vina, L., Dickerson, J. H., Camino, F., & Mendez, E. O. (1999). Spin-Dependent Exciton-Exciton Interaction in Quantum Wells under an Electric Field. Wiley Online Library. https://doi.org/10.1002/(SICI)1521-3951(199909)215:1<223::AID-PSSB223>3.0.CO;2-3
  - BibTeX
  BibTeX
  @article{noauthororeditor, abstract = {We give conclusive experimental evidence that spin‐dependent exciton–exciton interaction processes can be altered by directly modifying the spatial exciton structure applying an electric field. The previously observed energy splitting in spin‐polarized, dense exciton gases can be varied by the electric field from a maximum of 4 meV to 0 meV. On the basis of an earlier developed theoretical model it is seen that inter‐exciton scattering processes dominating at zero field are quenched and others are enhanced on increasing the field strength.}, author = {Aichmayer, G and Jetter, M. and Vina, L. and Dickerson, J.H. and Camino, F. and Mendez, E.O.}, doi = {https://doi.org/10.1002/(SICI)1521-3951(199909)215:1<223::AID-PSSB223>3.0.CO;2-3}, journal = { Wiley Online Library }, title = {Spin-Dependent Exciton-Exciton Interaction in Quantum Wells under an Electric Field}, year = 1999 }
1998
1. Homburg, O., Michler, P., Wenisch, H., Behringer, M., Gutowski, J., & and D. Hommel. (1998). Gain mechanisms in ZnSe based separate-confinement-heterostructure lasers with binary wells. /brokenurl#NULL
  - BibTeX
  - Link
  BibTeX
  @proceedings{noauthororeditor, author = {Homburg, O. and Michler, P. and Wenisch, H. and Behringer, M. and Gutowski, J. and and D. Hommel}, title = {Gain mechanisms in ZnSe based separate-confinement-heterostructure lasers with binary wells}, url = {/brokenurl#NULL}, year = 1998 }
  Link
  /brokenurl#NULL

Roman Bek

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2013