Dr. Joerg-Reinhardt Kropp Profile

Dr. Joerg-Reinhardt Kropp

at VI Systems GmbH

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Author

Publications (24)

Proceedings Article | 20 June 2024 Presentation + Paper

Monolithically integrated optical computing component for photonic matrix multiplication based on electro-optically modulated vertical-cavity surface-emitting lasers

N. Ledentsov, J. Dijkstra, O. Yu. Makarov, V. Shchukin, L. Chorchos, J.-R. Kropp, W. H. Pernice

Proceedings Volume 13002, 130020D (2024) https://doi.org/10.1117/12.3017020

KEYWORDS: Electrooptic modulation, Vertical cavity surface emitting lasers, Optical computing, Modulation, Waveguides, Matrix multiplication, Integrated optics, Electrooptics, Artificial intelligence

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Proceedings Article | 13 March 2024 Presentation + Paper

Analysis of laterally-coupled-cavity VCSELs for ultra-high-frequency photon-photon resonance modulation

N. Ledentsov, V. Shchukin, Ł. Chorchos, O. Yu. Makarov, J.-R. Kropp, I. Titkov, V. Kalosha, V. Zerova, M. Lindemann, N. Gerhardt, M. D’Alessandro, V. Torrelli, P. Debernardi, A. Tibaldi, M. Hofmann

Proceedings Volume 12904, 1290405 (2024) https://doi.org/10.1117/12.3001177

KEYWORDS: Vertical cavity surface emitting lasers, Modulation, Modulation frequency, Laser frequency, Frequency response, Streak cameras, Oscilloscopes, Near field, Single mode fibers, Data acquisition

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Proceedings Article | 17 March 2023 Presentation

100Gb/s short wavelength VCSELs applying a multi-aperture approach

Lukasz Chorchos, Nikolay Ledentsov, Oleg Makarov, Vitaly Shchukin, Nikolai Ledentsov, Joerg-R. Kropp, Jaroslaw Turkiewicz

Proceedings Volume PC12439, PC1243904 (2023) https://doi.org/10.1117/12.2650389

KEYWORDS: Vertical cavity surface emitting lasers, Resistance, Patents, Near field optics, Near field, Multimode fibers, Fiber lasers, Data transmission

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Proceedings Article | 3 March 2022 Presentation + Paper

Advances in design and application of compact VCSEL arrays: from multicore fiber to optical wireless and beyond

N. Ledentsov, L. Chorchos, O. Yu. Makarov, M. Bou Sanayeh, J.-R. Kropp, I. Titkov, V. Shchukin, V. Kalosha, J. Turkiewicz

Proceedings Volume 12020, 1202008 (2022) https://doi.org/10.1117/12.2607878

KEYWORDS: Vertical cavity surface emitting lasers, Data transmission, Multimode fibers, Modulation, Receivers, Oxides, Optical interconnects, Fiber couplers, Signal generators

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Proceedings Article | 1 August 2021 Presentation + Paper

Frequency characteristics of the polarization self‐modulation in oxide-confined vertical-cavity surface-emitting lasers

N. Ledentsov, L. Chorchos, O. Yu. Makarov, M. Bou Sanayeh, J.-R. Kropp, V. Shchukin, V. Kalosha, J. Turkiewicz

Proceedings Volume 11805, 118050X (2021) https://doi.org/10.1117/12.2593195

KEYWORDS: Vertical cavity surface emitting lasers, Near field optics, Polarization, Birefringence, Near field, Switching, Modulation, Reflection, Receivers, Antireflective coatings

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Proceedings Article | 5 March 2021 Presentation + Paper

Narrow spectrum VCSEL development for high performance 100G transceivers and increased transmission distance over multimode fiber

N. Ledentsov, L. Chorchos, O. Makarov, J.-R. Kropp, V. Shchukin, V. Kalosha, J. Turkiewicz

Proceedings Volume 11704, 117040P (2021) https://doi.org/10.1117/12.2578216

KEYWORDS: Vertical cavity surface emitting lasers, Multimode fibers, Transceivers, Data processing, Receivers, Interfaces, Electronics

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Proceedings Article | 24 February 2020 Paper

Oxidation stress induced birefringence in vertical cavity surface emitting lasers

N. Ledentsov, L. Chorchos, O. Makarov, J. -R. Kropp, V. Shchukin, V. P. Kalosha, Urs Hecht, P. Kurth, F. Gerfers, J. P. Turkiewicz, N. N. Ledentsov

Proceedings Volume 11300, 113000K (2020) https://doi.org/10.1117/12.2542972

KEYWORDS: Vertical cavity surface emitting lasers, Polarization, Birefringence, Near field optics, Switching, Near field, Multimode fibers, Data transmission, Receivers, Modulation

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Proceedings Article | 24 February 2020 Presentation + Paper

Quantum-dot oxide-confined 850-nm VCSELs with extreme temperature stability operating at 25 Gbit/s up to 180deg C

N. Ledentsov, L. Chorchos, O. Makarov, J.-R. Kropp, V. A. Shchukin, V. P. Kalosha, J. P. Turkiewicz, N. Cherkashin, N. N. Ledentsov

Proceedings Volume 11300, 113000H (2020) https://doi.org/10.1117/12.2543244

KEYWORDS: Vertical cavity surface emitting lasers, Quantum wells, Temperature metrology, Data transmission, Semiconducting wafers, Oxides, Resistance, Eye, Pulsed laser operation, Multimode fibers

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Proceedings Article | 1 March 2019 Presentation + Paper

Energy efficient 850-nm VCSEL based optical transmitter and receiver link capable of 56 Gbit/s NRZ operation

N. Ledentsov Jr., M. Agustin, L. Chorchos, J.-R. Kropp, V. Shchukin, V. Kalosha, M. Koepp, C. Caspar, J. Turkiewicz, N. Ledentsov

Proceedings Volume 10938, 109380J (2019) https://doi.org/10.1117/12.2509916

KEYWORDS: Vertical cavity surface emitting lasers, Receivers, Modulation, Transmitters, Optical fabrication, Oscilloscopes, Optical fabrication equipment, Energy efficiency, Connectors

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Proceedings Article | 19 February 2018 Paper

Temperature stable oxide-confined 850-nm VCSELs operating at bit rates up to 25 Gbit/s at 150ºC

N. Ledentsov, M. Agustin, J.-R. Kropp, V. Shchukin, V. Kalosha, K. Chi, Z. Khan, J. W. Shi

Proceedings Volume 10552, 105520P (2018) https://doi.org/10.1117/12.2318015

KEYWORDS: Vertical cavity surface emitting lasers, Eye, Temperature metrology, Oxides, Data transmission, Near field, Data communications, Multimode fibers, Fiber lasers, Waveguides

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Proceedings Article | 19 February 2018 Paper

50 Gb/s NRZ and 4-PAM data transmission over OM5 fiber in the SWDM wavelength range

M. Agustin, N. Ledentsov, J.-R. Kropp, V. Shchukin, V. Kalosha, K. Chi, Z. Khan, J. W. Shi

Proceedings Volume 10552, 1055202 (2018) https://doi.org/10.1117/12.2289823

KEYWORDS: Vertical cavity surface emitting lasers, Eye, Data transmission, Picosecond phenomena, Modulation, Digital signal processing, Signal attenuation, Forward error correction, Dispersion, Multimode fibers

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Proceedings Article | 19 February 2018 Paper

Thermally stable surface-emitting tilted wave laser

V. Shchukin, N. Ledentsov, V. Kalosha, M. Agustin, J. R. Kropp, M. Maximov, F. Zubov, Yu. M. Shernyakov, A. Payusov, N. Yu Gordeev, M. Kulagina, A. Zhukov

Proceedings Volume 10552, 1055207 (2018) https://doi.org/10.1117/12.2290565

KEYWORDS: Vertical cavity surface emitting lasers, Electroluminescence, Refractive index, Waveguides, Semiconductors, Near field

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Novel lasing modes in a vertical-cavity surface-emitting laser (VCSEL)-type structure based on an antiwaveguding cavity are studied. Such a VCSEL cavity has an effective refractive index in the cavity region lower than the average index of the distributed Bragg reflectors (DBRs). Such device in a stripe geometry does not support in–plane waveguiding mode, and all modes with a high Q-factor are exclusively VCSEL-like modes with similar near field profile in the vertical direction. A GaAlAs–based VCSEL structure studied contains a resonant cavity with multiple GaInAs quantum wells as an active region. The VCSEL structure is processed as an edge-emitting laser with cleaved facets and top contact representing a non–alloyed metal grid. Rectangular-shaped ~400x400 µm pieces are cleaved with perpendicular facets. The contact grid region has a total width of ~70 μm. 7 μm–wide metal stripes serve as non–alloyed metal contact and form periodic rectangular openings having a size of 10x40 μm. Surface emission through the windows on top of the chip is measured at temperatures from 90 to 380 K. Three different types of modes are observed. The longest wavelength mode (mode A) is a VCSEL–like mode at ~854 nm emitting normal to the surface with a full width at half maximum (FWHM) of the far field ~10°. Accordingly the lasing wavelength demonstrates a thermal shift of the wavelength of 0.06 nm/K. Mode B is at shorter wavelengths of ~840 nm at room temperature, emitting light at two symmetric lobes at tilt angles ~40° with respect to the normal to the surface in the directions parallel to the stripe. The emission wavelength of this mode shifts at a rate 0.22 nm/K according to the GaAs bandgap shift. The angle of mode B with respect to the normal reduces as the wavelength approaches the vertical cavity etalon wavelength and this mode finally merges with the VCSEL mode. Mode B hops between different lateral modes of the VCSEL forming a dense spectrum due to significant longitudinal cavity length, and the thermal shift of its wavelength is governed by the shift of the gain spectrum. The most interesting observation is Mode C, which shifts at a rate 0.06 nm/K and has a spectral width of ~1 nm. Mode C matches the wavelength of the critical angle for total internal reflection for light impinging from semiconductor chip on semiconductor/air interface and propagates essentially as an in–plane mode. According to modeling data we conclude that the lasing mode represents a coupled state between the TM–polarized surface–trapped optical mode and the VCSEL cavity mode. The resulting mode has an extended near field zone and low propagation losses. The intensity of the mode drastically enhances once is appears at resonance with Mode B. A clear threshold is revealed in the L–I curves of all modes and there is a strong competition of the lasing mechanisms once the gain maximum is scanned over the related wavelength range by temperature change.

Proceedings Article | 7 August 2017 Paper

High speed data transmission with a modal filter

L. Chorchos, G. Stepniak, J. Turkiewicz, L. Szostkiewicz, M. Napierala, L. Ostrowski, B. Bienkowska, T. Nasilowski, J. Kropp, N. Ledentsov, V. Shchukin

Proceedings Volume 10445, 1044516 (2017) https://doi.org/10.1117/12.2281038

KEYWORDS: Vertical cavity surface emitting lasers, Optical filters, Eye, Multimode fibers, Data transmission, Signal attenuation, Electronic filtering, Fiber lasers, Manufacturing, Signal processing

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Proceedings Article | 25 February 2017 Presentation + Paper

Robustness versus thermal effects of single-mode operation of vertical-cavity surface-emitting lasers with engineered leakage of high-order transverse optical modes

V. Kalosha, V. Shchukin, N. Ledentsov, J.-R. Kropp

Proceedings Volume 10122, 101220K (2017) https://doi.org/10.1117/12.2253021

KEYWORDS: Vertical cavity surface emitting lasers, Oxides, Laser optics, Laser applications, Distributed Bragg reflectors, Refractive index, Control systems, Absorption, Thermography, 3D modeling, Thermal effects, Dielectrics, Semiconductors, Thermal modeling

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Proceedings Article | 16 February 2017 Presentation + Paper

Resonant cavity light–emitting diodes based on dielectric passive cavity structures

N. Ledentsov, V. Shchukin, J.-R. Kropp, L. Zschiedrich, F. Schmidt

Proceedings Volume 10124, 101240O (2017) https://doi.org/10.1117/12.2253089

KEYWORDS: Dielectrics, Light emitting diodes, Semiconductors, Photonic crystals, Etching, Diodes, Distributed Bragg reflectors, Vertical cavity surface emitting lasers, Multilayers, Refractive index, Oxides, Light sources, Light, Quantum wells

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A novel design for high brightness planar technology light-emitting diodes (LEDs) and LED on-wafer arrays on absorbing substrates is proposed. The design integrates features of passive dielectric cavity deposited on top of an oxide– semiconductor distributed Bragg reflector (DBR), the p–n junction with a light emitting region is introduced into the top semiconductor λ/4 DBR period. A multilayer dielectric structure containing a cavity layer and dielectric DBRs is further processed by etching into a micrometer–scale pattern. An oxide–confined aperture is further amended for current and light confinement. We study the impact of the placement of the active region into the maximum or minimum of the optical field intensity and study an impact of the active region positioning on light extraction efficiency. We also study an etching profile composed of symmetric rings in the etched passive cavity over the light emitting area. The bottom semiconductor is an AlGaAs–AlAs multilayer DBR selectively oxidized with the conversion of the AlAs layers into AlO_x to increase the stopband width preventing the light from entering the semiconductor substrate. The approach allows to achieve very high light extraction efficiency in a narrow vertical angle keeping the reasonable thermal and current conductivity properties. As an example, a micro-LED structure has been modeled with AlGaAs-AlAs or AlGaAs-AlO_x DBRs and an active region based on InGaAlP quantum well(s) emitting in the orange spectral range at ~610 nm. A passive dielectric SiO₂ cavity is confined by dielectric Ta₂O₅/SiO₂ and AlGaAs-AlO_x DBRs. Cylindrically–symmetric structures with multiple ring patterns are modeled. It is demonstrated that the extraction coefficient of light to the air can be increased from 1.3% up to above 90% in a narrow vertical angle (full width at half maximum (FWHM) below 20°). For very small oxide–confined apertures ~100nm the narrowing of the FWHM for light extraction can be reduced down to 5°. Consequently high efficiency high brightness arrays of micro-LEDs becomes possible. For single emitters the approach is particularly interesting for oscillator strength engineering allowing high speed data transmission and for single photonics applying single quantum dot (QD) emitters and allowing >90% coupling of the emission into single mode fiber. We also note that for longer wavelength (~1300nm) QDs the thickness of the layers and surface patterns significantly increase allowing greatly reduced processing tolerances and applying further simplifications due to the possibility of using high contrast GaAs-AlO_x DBRs.

Proceedings Article | 10 February 2017 Paper

High speed 850 nm single mode and multi mode VCSEL transmission over multimode fiber

Łukasz Chorchos, Jarosław Turkiewicz, J. Kropp, N. Ledentsov, V. Shchukin, M. Agustin

Proceedings Volume 10325, 103250T (2017) https://doi.org/10.1117/12.2271043

KEYWORDS: Vertical cavity surface emitting lasers, Multimode fibers, Optical fibers

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Proceedings Article | 10 February 2017 Paper

Relative intensity noise of single- and multi-mode 850 nm vertical-cavity surface-emitting lasers

Łukasz Chorchos, Jarosław Turkiewicz, J. Kropp, N. Ledentsov, V. Shchukin, M. Agustin

Proceedings Volume 10325, 103250J (2017) https://doi.org/10.1117/12.2271089

KEYWORDS: Vertical cavity surface emitting lasers

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Proceedings Article | 10 February 2017 Paper

Impact of the sample modal composition of 850nm VCSELs on high speed data transmission over multimode fiber applying different modulation formats

J.-R. Kropp, N. Ledentsov, M. Agustin, V. Shchukin, J. Turkiewicz, I. Eddie

Proceedings Volume 10325, 103250W (2017) https://doi.org/10.1117/12.2271051

KEYWORDS: Vertical cavity surface emitting lasers, Multimode fibers, Modulation, Data transmission, Data communications

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Proceedings Article | 4 March 2016 Paper

Direct visualization of the in-plane leakage of high-order transverse modes in vertical-cavity surface-emitting lasers mediated by oxide-aperture engineering

N. Ledentsov, V. Shchukin, J.-R. Kropp, S. Burger, F. Schmidt

Proceedings Volume 9766, 976608 (2016) https://doi.org/10.1117/12.2208909

KEYWORDS: Vertical cavity surface emitting lasers, Oxides, Visualization, Modulation, Electroluminescence, 3D modeling, Data modeling, Zinc, CCD cameras, Neodymium, Ions

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Proceedings Article | 4 March 2016 Paper

Close to 100 Gbps discrete multitone transmission over 100m of multimode fiber using a single transverse mode 850nm VCSEL

Bo Wu, Xian Zhou, Yanan Ma, Jun Luo, Kangping Zhong, Shaofeng Qiu, Zhiyong Feng, Yazhi Luo, Mikel Agustin, Nikolay Ledentsov, Joerg Kropp, Vitaly Shchukin, Iain Eddie, Lu Chao

Proceedings Volume 9766, 97660K (2016) https://doi.org/10.1117/12.2208901

KEYWORDS: Vertical cavity surface emitting lasers, Multimode fibers, Data transmission, Optical interconnects, Forward error correction, Modulation, Digital signal processing, Oxides, Electroluminescence, Optical microscopy

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Proceedings Article | 11 September 2015 Paper

Adaptive optical interconnects: the ADDAPT project

Ronny Henker, Jan Pliva, Mahdi Khafaji, Frank Ellinger, Thomas Toifl, Bert Offrein, Alessandro Cevrero, Ilter Oezkaya, Marc Seifried, Nikolay Ledentsov, Joerg-R. Kropp, Vitaly Shchukin, Martin Zoldak, Leos Halmo, Jaroslaw Turkiewicz, Wyn Meredith, Iain Eddie, Michael Georgiades, Savvas Charalambides, Jeroen Duis, Pieter van Leeuwen

Proceedings Volume 9662, 966207 (2015) https://doi.org/10.1117/12.2202564

KEYWORDS: Transceivers, Optical interconnects, Switching, Data centers, Data communications, Optical components, Clocks, Modulation, Telecommunications, Optical networks

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Proceedings Article | 20 March 2015 Paper

Engineering of optical modes in vertical-cavity microresonators by aperture placement: applications to single-mode and near-field lasers

V. Shchukin, N. Ledentsov, J.-R. Kropp, G. Steinle, K. Choquette, S. Burger, F. Schmidt

Proceedings Volume 9381, 93810V (2015) https://doi.org/10.1117/12.2077012

KEYWORDS: Vertical cavity surface emitting lasers, Oxides, Near field optics, Near field, Refractive index, 3D modeling, Waveguides, Reflectivity, Resistance, Semiconductors

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Proceedings Article | 9 March 2015 Paper

850 nm single mode VCSEL-based 25Gx16 transmitter/receiver boards for parallel signal transmission over 1 km of multimode fiber

J.-R. Kropp, V. Shchukin, N. Ledentsov, George Schaefer, Nikolay Ledentsov, Bo Wu, Qiu Shaofeng, Ma Yanan, Feng Zhiyong, Jarek Turkiewicz

Proceedings Volume 9390, 93900C (2015) https://doi.org/10.1117/12.2080882

KEYWORDS: Vertical cavity surface emitting lasers, Data transmission, Multimode fibers, Eye, Receivers, Optical fabrication, Transmitters, Optics manufacturing, Transceivers, Connectors

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Proceedings Article | 4 March 2015 Paper

High-speed modulation, wavelength, and mode control in vertical-cavity surface-emitting lasers

Nikolay Ledentsov, Jörg-R. Kropp, Vitaly Shchukin, Gunther Steinle, Jarek Turkiewicz, Bo Wu, Shaofeng Qiu, Yanan Ma, Zhiyong Feng, Sven Burger, Frank Schmidt, Christoph Caspar, Ronald Freund, Kent Choquette

Proceedings Volume 9381, 93810F (2015) https://doi.org/10.1117/12.2082951

KEYWORDS: Vertical cavity surface emitting lasers, Modulation, Oxides, Optical fibers, Multimode fibers, Dielectrics, Electro optics, Dispersion, Photonic crystals, Near field

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