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Hader J.,Nonlinear Control Strategies Inc. | Hader J.,University of Arizona | Moloney J.V.,Nonlinear Control Strategies Inc. | Moloney J.V.,University of Arizona | Koch S.W.,University of Marburg
Applied Physics Letters | Year: 2011

The temperature dependence of the measured internal efficiencies of green and blue emitting InGaN-based diodes is analyzed. With increasing temperature, a strongly decreasing strength of the loss mechanism responsible for droop is found which is in contrast to the usually assumed behavior of Auger losses. However, the experimental observations can be well reproduced assuming density activated defect recombination with a temperature independent recombination time. © 2011 American Institute of Physics.


Heinen B.,University of Marburg | Wang T.-L.,University of Arizona | Sparenberg M.,University of Marburg | Weber A.,NAsP III V GmbH | And 6 more authors.
Electronics Letters | Year: 2012

A report is presented on an optically-pumped semiconductor disk laser providing a continuous-wave output power of 106W at a heatsink temperature of 3°C. The laser, which operates in the transversal multimode regime, emits at a wavelength of 1028nm. This high output power is achieved by carefully optimising the chip design, the growth process, and the bonding layer. © 2012 The Institution of Engineering and Technology.


Hader J.,Nonlinear Control Strategies Inc. | Hader J.,University of Arizona | Moloney J.V.,Nonlinear Control Strategies Inc. | Moloney J.V.,University of Arizona | Koch S.W.,University of Marburg
Applied Physics Letters | Year: 2014

Fully microscopic many-body calculations are used to analyze the carrier dynamics in situations where a strong sub-picosecond pulse interacts with an inverted semiconductor quantum well. Electron-electron and electron-phonon scatterings are calculated on a second Born-Markov level. Intra-subband scatterings on a scale of tens of femtoseconds are shown to quickly re-fill the kinetic holes created in the carrier distributions during the pulse amplification. Even for sub-100 fs pulses, this significantly influences the pulse amplification as well as its spectral dependence. Interband scatterings on a few picosecond timescale limit the possibly achievable repetition rate in pulsed semiconductor lasers. © 2014 AIP Publishing LLC.


Wang T.-L.,University of Arizona | Heinen B.,University of Marburg | Hader J.,University of Arizona | Hader J.,Nonlinear Control Strategies Inc. | And 10 more authors.
Laser and Photonics Reviews | Year: 2012

Combining rigorous quantum epitaxial design, highly accurate growth, novel processing and thermal management pushes the output power of single chip vertical-external-cavity surface-emitting lasers (VECSELs) beyond the 100 W milestone. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Hader J.,Nonlinear Control Strategies Inc. | Hader J.,University of Arizona | Moloney J.V.,Nonlinear Control Strategies Inc. | Moloney J.V.,University of Arizona | Koch S.W.,University of Marburg
Applied Physics Letters | Year: 2010

It is shown that a carrier loss process modeling density-activated defect recombination can reproduce the experimentally observed droop of the internal quantum efficiency in GaN-based laser diodes. © 2010 American Institute of Physics.


Hader J.,Nonlinear Control Strategies Inc. | Hader J.,University of Arizona | Moloney J.V.,Nonlinear Control Strategies Inc. | Moloney J.V.,University of Arizona | Koch S.W.,University of Marburg
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Fully microscopic many-body models are used to calculate the radiative losses in GaN-based light emitting devices. It is shown how simpler models under-estimate these losses significantly. Using the high accuracy of the models allows to eliminate the corresponding loss parameter (B) and its density- and temperature dependence from the space of parameters that are used to fit effuciency data. This allows to study the dependencies of the remaining processes with high accuracy. Using this model, it is show that many processes that have been proposed as causes for the efficiency droop either have wrong dependencies, magnitudes or require unreasonable assumptions to explain the phenomena in general. The most plausible droop model appears to be a combination of carrier delocalization at very low temperatures and pump powers, density- activated defect-recombination at low to medium pumping and injection/escape losses at strong pumping. © 2013 SPIE.


Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 150.00K | Year: 2015

ABSTRACT: The proposal overall objective is to develop a rigorous understanding of the electronic structure and semiconductor-laser application related physics properties of the novel III-V-Bi material system. The sophisticated, graphical user interface driven software tools already established for standard III-V semiconductor heterostructures will be extended and generalized to become applicable for the bismide system. Detailed theory-experiment comparisons will be performed to establish a reliable materials data base. Using this as input for the systematic, fully microscopic calculations of the gain and intrinsic losses will allow for rigorous physics-based modeling of III-V-Bi based optoelectronic devices. This approach will make it possible to design, guide and provide feedback on growth, fabrication and evaluation of semiconductor quantum-confined structures with type-I or type-II band alignment that provide optical gain in the 3-5 m (0.41 to 0.25 eV) window. The key technical objective of Phase I is a proof of concept study to establish the potential of III-V-Bi based material systems as lasers operating in 3-5 m window at watt-level powers. This will be pursued via a comprehensive literature search and evaluation of atomistic level bandstructure calculation methods, validation of these and of NLCSTRs microscopic modeling tools against experimental data provided by subcontractor Arizona State University BENEFIT: The strong demand for high quality semiconductor laser systems for dual-use technologies that must satisfy stringent military specifications as well as future state-of-the-art commercial applications, creates a critical need for a commercial software package that can leverage a cost effective, fast track to the final laser product. Future improvements in semiconductor wafer growth quality will require the implementation of improved wafer processing diagnostics during in-situ growth within MBE and MOCVD systems. For example, state-of-the-art MBE growth systems contain multiple chambers designed to carry out wafer diagnostics during material growth. Future markets for such a software suite will include individual VCSELs, VCSEL arrays, high-power/brightness VECSELs, better performing semiconductor optical amplifiers (SOAs), higher slope efficiency edge emitters (both single mode, broad area and diode bars) etc. Existing semiconductor material technologies for the 3-5 m mid infrared range are severely limited by low gain, high losses, poor beam quality, low wall-plug efficiencies and, often, the need to operate at cryogenic temperatures. An approach to avoid many of these problems may be found by adding small amounts of bismuth to the conventional 3-5 micron materials. The mid-IR laser software design development has several potential applications to IRCM, ISR (Intelligence, Surveillance, Reconnaissance): LADAR, 3-D imaging, active illumination imaging in the mid-wave IR requiring sources that operate as efficiently as possible and at Watt power levels.


Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase II | Award Amount: 749.92K | Year: 2013

ABSTRACT: The objective of this project is to develop sophisticated, graphical user interface driven software tools built on fully microscopic physics to design, guide and provide feedback on growth, fabrication and evaluation of semiconductor structures that provide optical gain in the critical 2.4-4 micron window. The mid-IR laser software design development has several potential applications to IRCM, ISR (Intelligence, Surveillance, Reconnaissance): LADAR, 3-D imaging, active illumination imaging in the mid-wave IR requiring sources that operate as efficiently as possible. This efficiency"buys"the application more time to operate (say on battery charge), with a smaller power budget (no cryo-cooling, little or no cooling), imaging at a distance (bright laser sources) for relatively little cost (over solid state lasers of equivalent wavelength/power), C3 (Command, Control, and Communications): potential free-space optical communications for fast modulated semiconductors (high bandwidth), low cost, in relevant transmission window (lower observable than regions where commercially available imagers operate). Nonlinear Controls Strategies SimuLaseTM software will be extended to optimize QW/barrier epitaxial designs for mid-IR Type I and II semiconductor active structures. Loss channels i.e., Auger and free carrier absorption, will be efficiently implemented in the software modules. Test structures will be grown for validation and iterative optimization of the designs. BENEFIT: The strong demand for high quality semiconductor laser systems for dual-use technologies that must satisfy stringent military specifications as well as future state-of-the-art commercial applications, creates a critical need for a commercial software package that can leverage a cost effective, fast track to the final laser product. Future improvements in semiconductor wafer growth quality will require the implementation of improved wafer processing diagnostics during in-situ growth within MBE and MOCVD systems. For example, state-of-the-art MBE growth systems contain multiple chambers designed to carry out wafer diagnostics during material growth. Nonlinear Control Strategies Inc., already has a small but established customer base for its raw gain databases amongst leading semiconductor laser manufacturers. The proposed semiconductor laser design and in-situ growth diagnostic software will fill a critical void that currently exists across a broad base of modern technologies that rely almost exclusively on high performance semiconductor amplifiers or lasers as components in the important mid-IR window of the electromagnetic spectrum. NLCSTR is currently engaged with a defense prime on optimizing a specific mid-IR epitaxy for an IRCM application. By providing a software tool employed at the materials growth level, it will become possible to iteratively fast-track from design to a final operational laser source. The customer base for these software products will come from users who require high quality semiconductor materials growth to satisfy military specifications or high performance commercial applications. These include commercial semiconductor laser manufacturers, large and small, who require high performance semiconductor active components for either commercial or defense applications and DOD research scientists engaged at all levels of semiconductor laser diode development. Numerous defense related applications include countermeasures, stand-off detection of explosion hazards, eyesafe seekers for smart munitions, covert communications systems, remote detection and imaging of threat agents and chemical warfare agent detection. Commercial applications include noninvasive medical diagnostics, industrial process controls, remote gas leak detection, environmental and safety monitoring (greenhouse gases, hydrocarbons, emissions reduction); mid-IR spectroscopy; oil/gas exploration; bio- medical diagnostics, LIDAR; and eye-safe illumination. Mid Infrared lasers (2-5µm) are also in great demand for a variety of applications including plastic and polymer processing, spectroscopy, laser scalpel, remote sensing, free space communications and pumping OPOs.


Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 100.00K | Year: 2011

ABSTRACT: The key objective of the proposal is to develop sophisticated, graphical user interface driven software tools built on fully microscopic physics to design, guide and provide feedback on growth, fabrication and evaluation of semiconductor structures that provide optical gain in the critical 2.4-4 micron wavelength window. Existing technologies are severely limited by low gain, high losses, poor beam quality, low wall-plug efficiencies and, often, the need to operate at cryogenic temperatures. Nonlinear Control Strategies Inc. will develop state-of-the-art and unique proprietary software design tools to optimize the semiconductor epitaxial structures for room temperature laser operation in either edge or surface emitting geometries. A key design task will be to combine bandstructure engineering with full many-body microscopic physics calculations to reduce Auger and intraband absorption losses that dramatically limit performance in this wavelength window. The mid-IR laser software design development has several potential applications to IRCM, ISR (Intelligence, Surveillance, Reconnaissance): LADAR, 3-D imaging, active illumination imaging in the mid-wave IR requiring sources that operate as efficiently as possible. The anticipated outcome of the project in Phase 2 is a flexible software tool capable of rapid convergence to optimized solutions by running in parallel on multiple or multi-core processors and on specialized hardware accelerators BENEFIT: There currently exists a critical gap in the availability of semiconductor laser sources operating in the 2.4-4 micron mid-IR wavelength window. There is a dire need for high brightness laser sources that deliver Watts of power at room temperature on a small footprint. The mid-IR laser software design development has several potential applications to IRCM, ISR (Intelligence, Surveillance, Reconnaissance): LADAR, 3-D imaging, active illumination imaging in the mid-wave IR requiring sources that operate as efficiently as possible.


Trademark
Nonlinear Control Strategies Inc. | Date: 2010-05-18

Computer software for design and analysis of optoelectronic semiconductor devices.

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