Dr. Joerg-Reinhardt Kropp Profile

Dr. Joerg-Reinhardt Kropp

at VI Systems GmbH

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Author

Publications (16)

Proceedings Article | 1 March 2019

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

Proc. SPIE. 10938, Vertical-Cavity Surface-Emitting Lasers XXIII

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

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Proceedings Article | 19 February 2018

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

Proc. SPIE. 10552, Vertical-Cavity Surface-Emitting Lasers XXII

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

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Proceedings Article | 19 February 2018

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

Proc. SPIE. 10552, Vertical-Cavity Surface-Emitting Lasers XXII

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

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Proceedings Article | 19 February 2018

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

Proc. SPIE. 10552, Vertical-Cavity Surface-Emitting Lasers XXII

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

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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

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

Proc. SPIE. 10445, Photonics Applications in Astronomy, Communications, Industry, and High Energy Physics Experiments 2017

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

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Proceedings Article | 25 February 2017

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

Proc. SPIE. 10122, Vertical-Cavity Surface-Emitting Lasers XXI

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

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Proceedings Article | 16 February 2017

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

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

Proc. SPIE. 10124, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XXI

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

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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 AlOx 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-AlOx 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-AlOx 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-AlOx DBRs.

Proceedings Article | 10 February 2017

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

Proc. SPIE. 10325, Optical Fibers and Their Applications 2017

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

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Proceedings Article | 10 February 2017

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

Proc. SPIE. 10325, Optical Fibers and Their Applications 2017

KEYWORDS: Vertical cavity surface emitting lasers

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Proceedings Article | 10 February 2017

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

Proc. SPIE. 10325, Optical Fibers and Their Applications 2017

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

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Proceedings Article | 4 March 2016

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

Proc. SPIE. 9766, Vertical-Cavity Surface-Emitting Lasers XX

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

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Proceedings Article | 4 March 2016

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

Proc. SPIE. 9766, Vertical-Cavity Surface-Emitting Lasers XX

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

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Proceedings Article | 11 September 2015

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

Proc. SPIE. 9662, Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2015

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

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Proceedings Article | 20 March 2015

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

Proc. SPIE. 9381, Vertical-Cavity Surface-Emitting Lasers XIX

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

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Proceedings Article | 9 March 2015

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

Proc. SPIE. 9390, Next-Generation Optical Networks for Data Centers and Short-Reach Links II

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

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Proceedings Article | 4 March 2015

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

Proc. SPIE. 9381, Vertical-Cavity Surface-Emitting Lasers XIX

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

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Showing 5 of 16 publications

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