Center for Quantum Devices - Most Downloaded Journal Articles

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17.	High Optical Response in Forward Biased (In,Ga)N-GaN Multiquantum-Well Diodes Under Barrier Illumination J.L. Pau, R. McClintock, C. Bayram, K. Minder, D. Silversmith and M. Razeghi IEEE Journal of Quantum Electronics, Vol. 44, No. 4, p. 346-353.-- April 1, 2008 ...[Visit Journal] The authors report on the current–voltage (I–V) characteristic under forward biases obtained in low leakage, small size p-(In,Ga)N–GaN-n multiquantum well diodes. Under barrier illumination, the devices present a high optical response with capabilities to detect optical powers in the pW range without further amplification. This response is attributed to the screening of the internal electric fields. Recombination times of a few seconds are found to be associated to this mechanism. Moreover, a step-like feature is found in the I– V characteristic before the diode turn-on voltage. Our model proposes tunneling current through the multi-quantum-well structure as responsible of this feature. Fast modulation of the tunneling effect under barrier illumination is used to evaluate the detection of low photon fluxes. [reprint (PDF)]
17.	Infrared detection from GaInAs/InP nanopillar arrays A. Gin, B. Movaghar, M. Razeghi and G.J. Brown Nanotechnology 16-- July 1, 2005 ...[Visit Journal] We report on the photoresponse from large arrays of 40 nm radius nanopillars with sensitivity in the long-wavelength infrared regime. Using photoluminescence techniques, a peak wavelength blue shift of approximately 5 meV was observed at 30 K from GaInAs/InP nanopillar structures, indicating carrier confinement effects. Responsivity measurements at 30 K indicated peak wavelength response at about 8 µm with responsivity of 420 mA/W at −2 V bias. We have also measured the noise and estimated the peak detectivity to be 3×10⁸ cm·Hz^½·W⁻¹ at 1 V reverse bias and 30 K. A maximum internal quantum efficiency of 4.5% was derived from experiment. Both the photo and the dark transport have been successfully modeled as processes that involve direct and indirect field-assisted tunneling as well as thermionic emission. The best agreement with experiment was obtained when allowances were made for the non-uniformity of barrier widths and electric field heating of carriers above the lattice temperature. [reprint (PDF)]
17.	Advances in mid-infrared detection and imaging: a key issues review Manijeh Razeghi and Binh-Minh Nguyen Rep. Prog. Phys. 77 (2014) 082401-- August 4, 2014 ...[Visit Journal] It has been over 200 years since people recognized the presence of infrared radiation, and developed methods to capture this signal. However, current material systems and technologies for infrared detections have not met the increasing demand for high performance infrared detectors/cameras, with each system having intrinsic drawbacks. Type-II InAs/GaSb superlattice has been recently considered as a promising candidate for the next generation of infrared detection and imaging. Type-II superlattice is a man-made crystal structure, consisting of multiple quantum wells placed next to each other in a controlled way such that adjacent quantum wells can interact. The interaction between multiple quantum wells offers an additional degree of freedom in tailoring the material's properties. Another advantage of type-II superlattice is the experimental benefit of inheriting previous research on material synthesis and device fabrication of bulk semiconductors. It is the combination of these two unique strengths of type-II superlattice—novel physics and easy manipulation—that has enabled unprecedented progress in recent years. In this review, we will describe historical development, and current status of type-II InAs/GaSb superlattice for advanced detection and imaging in the mid-infrared regime (λ = 3–5 µm). [reprint (PDF)]
17.	Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices with an AlAsSb/GaSb superlattice barrier A. Haddadi, R. Chevallier, A. Dehzangi, and M. Razeghi Applied Physics Letters 110, 101104-- March 8, 2017 ...[Visit Journal] Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices on GaSb substrate have been demonstrated. An AlAsSb/GaSb H-structure superlattice design was used as the large-bandgap electron-barrier in these photodetectors. The photodetector is designed to have a 100% cut-off wavelength of ∼2.8 μm at 300 K. The photodetector exhibited a room-temperature (300 K) peak responsivity of 0.65 A/W at 1.9 μm, corresponding to a quantum efficiency of 41% at zero bias under front-side illumination, without any anti-reflection coating. With an R × A of 78 Ω·cm² and a dark current density of 8 × 10⁻³ A/cm² under −400 mV applied bias at 300 K, the nBn photodetector exhibited a specific detectivity of 1.51 × 10¹⁰ Jones. At 150 K, the photodetector exhibited a dark current density of 9.5 × 10⁻⁹ A/cm² and a quantum efficiency of 50%, resulting in a detectivity of 1.12 × 10¹³ Jones. [reprint (PDF)]
17.	Long-Wavelength Infrared Photodetectors Based on InSbBi Grown on GaAs Substrates J.J. Lee, J.D. Kim, and M. Razeghi Applied Physics Letters 71 (16)-- October 20, 1997 ...[Visit Journal] We demonstrate the operation of InSbBi infrared photoconductive detectors grown by low-pressure metalorganic chemical vapor deposition on semi-insulating GaAs substrates. The fabricated photodetector showed a cutoff wavelength of 7.7 μm at 77 K. The responsivity of the InSbBi photodetector at 7 μm was about 3.2 V/W at 77 K. The corresponding Johnson-noise limited detectivity was 4.7×10⁸ cm· Hz^½/W. The carrier lifetime was estimated to be about 86 ns from the voltage-dependent responsivity measurements. [reprint (PDF)]
17.	Gas sensing spectroscopy system utilizing a sample grating distributed feedback quantum cascade laser array and type II superlattice detector Nathaniel R. Coirier; Andrea I. Gomez-Patron; Manijeh Razeghi Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 1128815-- January 31, 2020 ...[Visit Journal] Gas spectroscopy is a tool that can be used in a variety of applications. One example is in the medical field, where it can diagnose patients by detecting biomarkers in breath, and another is in the security field, where it can safely alert personnel about ambient concentrations of dangerous gas. In this paper, we document the design and construction of a system compact enough to be easily deployable in defense, healthcare, and chemical safety environments. Current gas sensing systems use basic quantum cascade lasers (QCLs) or distributed feedback quantum cascade lasers (DFB QCLs) with large benchtop signal recovery systems to determine gas concentrations. There are significant issues with these setups, namely the lack of laser tunability and the lack of practicality outside of a very clean lab setting. QCLs are advantageous for gas sensing purposes because they are the most efficient lasers at the mid infrared region (MIR). This is necessary since gases tend to have stronger absorption lines in the MIR range than in the near-infrared (NIR) region. To incorporate the efficiency of a QCL with wide tuning capabilities in the MIR region, sampled grating distributed feedback (SGDFB) QCLs are the answer as they have produced systems that are widely tunable, which is advantageous for scanning a robust and complete absorption spectrum. The system employs a SGDFB QCL array emitter, a Type II InAsSb Superlattice detector receiver, a gas cell, and a cooling system. [reprint (PDF)]
17.	Polarization-free GaN emitters in the ultraviolet and visible spectra via heterointegration on CMOS-compatible Si (100) C. Bayram, J. Ott, K. T. Shiu, C. W. Cheng, Y. Zhu, J. Kim, D. K. Sadana, M. Razeghi Proc. SPIE 9370, Quantum Sensing and Nanophotonic Devices XII, 93702F -- February 8, 2015 ...[Visit Journal] This work presents a new type of polarization-free GaN emitter. The unique aspect of this work is that the ultraviolet and visible emission originates from the cubic phase GaN and the cubic phase InGaN/GaN multi-quantum-wells, respectively. Conventionally, GaN emitters (e.g. light emitting diodes, laser diodes) are wurtzite phase thus strong polarization fields exist across the structure contributing to the “droop” behavior – a phenomenon defined as “the reduction in emitter efficiency as injection current increases”. The elimination of piezoelectric fields in GaN-based emitters as proposed in this work provide the potential for achieving a 100% internal efficiency and might lead to droopfree light emitting diodes. In addition, this work demonstrates co-integration of GaN emitters on cheap and scalable CMOS-compatible Si (100) substrate, which yields possibility of realizing a GaN laser diode uniquely – via forming mirrors along the naturally occurring cubic phase GaN-Si(100) cleavage planes. [reprint (PDF)]
17.	High Performance Quantum Cascade Lasers at λ ~ 6 μm M. Razeghi, S. Slivken, J. Yu, A. Evans, and J. David Microelectronics Journal, 34 (5-8)-- May 1, 2003 ...[Visit Journal] This talk will focus on the recent efforts at the Center for Quantum Devices to deliver a high average power quantum cascade laser source at λ ~6 μm. Strain-balancing is used to reduce leakage for these shorter wavelength quantum cascade lasers. Further, the effect of reducing the doping in the injector is explored relative to the threshold current density and maximum average output power. Lastly, to demonstrate more of the potential of these devices, epilayer down bonding is explored as a technique to significantly enhance device performance. [reprint (PDF)]
17.	Fabrication of 12 µm pixel-pitch 1280 × 1024 extended short wavelength infrared focal plane array using heterojunction type-II superlattice-based photodetector Arash Dehzangi , Abbas Haddadi, Romain Chevallier, Yiyun Zhang and Manijeh Razegh Semicond. Sci. Technol. 34, 03LT01-- February 4, 2019 ...[Visit Journal] We present an initial demonstration of a 1280 × 1024 extended short-wavelength infrared focal plane array (FPA) imager with 12μm pixel-pitch based on type–II InAs/AlSb/GaSb superlattice heterojunction photodetectors, with a novel bandstructure-engineered photo-generated carrier extractor as the window layer in the hetero structure to efﬁciently extract the photo-generated carriers. This heterostructure with a larger bandgap top window/contact layer leads to the device having lower dark current density compared to conventional pn junction devices. The large format FPA was fabricated with 12 μm pixel-pitch using a developed fabrication process. Test pixels fabricated separately exhibit 100% cut–off wavelengths of ∼2.22, ∼2.34μm, and ∼2.45μm at 150, 200K, and 300K. The test devices achieve saturated quantum efﬁciency values under zero bias of 54.3% and 68.4% at 150 and 300K, under back-side illumination and without any anti-reﬂection coating. At 150K, these photodetectors exhibit dark current density of 1.63 × 10⁻⁷ A·cm⁻² under −20mV applied bias providing a speciﬁc detectivity of 1.01 × 10¹¹ cm ·Hz^½/W at 1.9μm. [reprint (PDF)]
17.	Long-Wavelength InAsSb Photoconductors Operated at Near Room Temperatures (200-300 K) J.D. Kim, D. Wu, J. Wojkowski, J. Piotrowski, J. Xu, and M. Razeghi Applied Physics Letters., 68 (1),-- January 1, 1996 ...[Visit Journal] Long-wavelength InAs_1−xSb_x photoconductors operated without cryogenic cooling are reported. The devices are based on p-InAs_1−xSb_x/p-InSb heterostructures grown on (100) semi-insulating GaAs substrates by low pressure metalorganic chemical vapor deposition (LP‐MOCVD). Photoreponse up to 14 μm has been obtained in a sample with x=0.77 at 300 K, which is in good agreement with the measured infrared absorption spectra. The corresponding effective lifetime of ≊0.14 ns at 300 K has been derived from stationary photoconductivity. The Johnson noise limited detectivity at λ=10.6 μm is estimated to be about 3.27×10⁷ cm· Hz^½/W at 300 K. [reprint (PDF)]
17.	Demonstration of 256x256 Focal Plane Arrays Based on Al-free GaInAs/InP QWIP J. Jiang, K. Mi, R. McClintock, M. Razeghi, G.J. Brown, and C. Jelen IEEE Photonics Technology Letters 15 (9)-- September 1, 2003 ...[Visit Journal] We report the first demonstration of an infrared focal plane array based on aluminum-free GaInAs-InP quantum-well infrared photodetectors (QWIPs).A unique positive lithography method was developed to perform indium-bump liftoff. The noise equivalent differential temperature (NEΔT) of 29 mK was achieved at 70 K with f/2 optics. [reprint (PDF)]
17.	Room-temperature continuous-wave operation of quantum-cascade lasers at λ ~ 4 µm J.S. Yu, S.R. Darvish, A. Evans, J. Nguyen, S. Slivken, and M. Razeghi Applied Physics Letters 88 (4)-- January 23, 2006 ...[Visit Journal] High-power cw λ~4 μm quantum-cascade lasers (QCLs) are demonstrated. The effect of different cavity length and laser die bonding is also investigated. For a high-reflectivity-coated 11-μm-wide and 4-mm-long epilayer-down bonded QCL, cw output powers as high as 1.6 W at 80 K and 160 mW at 298 K are obtained, and the cw operation is achieved up to 313 K with 12 mW. [reprint (PDF)]
17.	Room temperature terahertz semiconductor frequency comb Quanyong Lu, Feihu Wang, Donghai Wu, Steven Slivken & Manijeh Razeghi Nature Communications 10, 2403-- June 3, 2019 ...[Visit Journal] A terahertz (THz) frequency comb capable of high-resolution measurement will significantly advance THz technology application in spectroscopy, metrology and sensing. The recently developed cryogenic-cooled THz quantum cascade laser (QCL) comb has exhibited great potentials with high power and broadband spectrum. Here, we report a room temperature THz harmonic frequency comb in 2.2 to 3.3 THz based on difference-frequency generation from a mid-IR QCL. The THz comb is intracavity generated via down-converting a mid-IR comb with an integrated mid-IR single mode based on distributed-feedback grating without using external optical elements. The grating Bragg wavelength is largely detuned from the gain peak to suppress the grating dispersion and support the comb operation in the high gain spectral range. Multiheterodyne spectroscopy with multiple equally spaced lines by beating it with a reference Fabry-Pérot comb confirms the THz comb operation. This type of THz comb will find applications to room temperature chip-based THz spectroscopy. [reprint (PDF)]
17.	Optical Coatings by ion-beam sputtering deposition for long-wave infrared quantum cascade lasers J. Nguyen, J.S. Yu, A. Evans, S. Slivken and M. Razeghi Applied Physics Letters, 89 (11)-- September 11, 2006 ...[Visit Journal] The authors report on the development of high-reflection and multilayer antireflection coatings using ion-beam sputtering deposition for long-wave infrared (λ~9.4 μm) quantum cascade lasers. A metallic high-reflection coating structure using Y₂O₃ and Au is demonstrated to achieve a high reflectance of 96.70%, and the use of a multilayer anti-reflection coating structure using PbTe and ZnO is demonstrated to achieve a very low reflectance of 1.64%. [reprint (PDF)]
17.	High operability 1024 x 1024 long wavelength infrared focal plane array base on Type-II InAs/GaSb superlattice A. Haddadi, S.R. Darvish, G. Chen, A.M. Hoang, B.M. Nguyen and M. Razeghi AIP Conference Proceedings, Vol. 1416, p. 56-58_NGS15 Conf_Blacksburg, VA_Aug 1-5, 2011-- December 31, 2011 ...[Visit Journal] Fabrication and characterization of a high performance 1024×1024 long wavelength infrared type‐II superlattice focal plane array are described. The FPA performs imaging at a continous rate of 15.00 frames/sec. Each pixel has pitch of 18μm with a fill factor of 71.31%. It demonstrates excellent operability of 95.8% and 97.4% at 81 and 68K operation temperature. The external quantum efficiency is ∼81% without any antireflective coating. Using F∕2 optics and an integration time of 0.13ms, the FPA exhibits an NEDT as low as 27 and 19mK at operating temperatures of 81 and 68K respectively. [reprint (PDF)]
17.	Recent progress of quantum cascade laser research from 3 to 12 μm at the Center for Quantum Devices MANIJEH RAZEGHI,* WENJIA ZHOU,STEVEN SLIVKEN,QUAN-YONG LU,DONGHAI WU, AND RYAN MCCLINTOC Applied Optics Vol. 56, No. 31 -- October 10, 2017 ...[Visit Journal] The quantum cascade laser (QCL) is becoming the leading laser source in the mid-infrared (mid-IR) range, which contains two atmospheric transmission windows and many molecular fingerprint absorption features. Since its first demonstration in 1994, the QCL has undergone tremendous development in terms of the output power, wall plug efficiency, wavelength coverage, tunability and beam quality. At the Center for Quantum Devices, we have demonstrated high-power continuous wave operation of QCLs covering a wide wavelength range from 3 to 12 μm, with power output up to 5.1 W at room temperature. Recent research has resulted in power scaling in pulsed mode with up to 203 W output, electrically tunable QCLs based on monolithic sampled grating design, heterogeneous QCLs with a broad spectral gain, broadly tunable on-chip beam-combined QCLs, QCL-based mid-IR frequency combs, and fundamental mode surface emitting quantum cascade ring lasers. The developed QCLs will be the basis for a number of next-generation spectroscopy and sensing systems. [reprint (PDF)]
17.	High power operation of λ ∼ 5.2–11 μm strain balanced quantum cascade lasers based on the same material composition N. Bandyopadhyay, Y. Bai, S. Slivken, and M. Razeghi Appl. Phys. Lett. 105, 071106 (2014)-- August 20, 2014 ...[Visit Journal] A technique based on composite quantum wells for design and growth of strain balanced Al_0.63In_0.37As/Ga_0.35In_0.65As/Ga_0.47In_0.53As quantum cascade lasers (QCLs) by molecular beam epitaxy (MBE), emitting in 5.2–11 μm wavelength range, is reported. The strained Al_0.63In_0.37As provides good electron confinement at all wavelengths, and strain balancing can be achieved through composite wells of Ga_0.35In_0.65As/Ga_0.47In_0.53As for different wavelength. The use of these fixed composition materials can avoid the need for frequent calibration of a MBE reactor to grow active regions with different strain levels for different wavelengths. Experimental results for QCLs emitting at 5.2, 6.7, 8.2, 9.1, and 11 μm exhibit good wall plug efficiencies and power across the whole wavelength range. It is shown that the emission wavelength can be predictably changed using the same design template. These lasers are also compatible with a heterogeneous broadband active region, consisting of multiple QCL cores, which can be produced in a single growth run. [reprint (PDF)]
17.	Novel Method for Reclaim/Reuse of Bulk GaN Substrates using Sacrifical ZnO Release Layers A. Rajan, S. Sundaram, Y. El Gmili, P. L. Voss, K. Pantzas, T. Moudakir, A. Ougazzaden, D. J. Rogers, F. Hosseini Teherani, V. E. Sandana, P. Bove, K. Prior, R. McClintock & M. Razeghi Proc. SPIE 8987, Oxide-based Materials and Devices V, 898719-- April 2, 2014 ...[Visit Journal] Free-standing (0002)-oriented GaN substrates (f = 2”) were coated with 200 nm of ZnO and used as templates for the growth of GaN thin films. SEM and AFM revealed that such GaN layers had a relatively homogenous surface morphology with an RMS roughness (5 μm x 5 μm) of less than 4nm. XRD studies revealed strained ZnO growth on the GaN substrate and the reproduction of the substrate rocking curve for the GaN overlayers after only a hundred nm of growth, thus indicating that the GaN films had superior crystallographic quality compared to those grown on sapphire or ZnO/sapphire substrates. Quarter-wafer areas of GaN were removed from the GaN substrate (by selective chemical etching away of the ZnO interlayer). The expensive GaN substrates were then reclaimed/reused (without the need for polishing) for a second cycle of ZnO and GaN growth, which gave similar XRD, SEM, CL and AFM results to the first cycle. [reprint (PDF)]
17.	Broadband monolithically-tunable quantum cascade lasers Wenjia Zhou, Ryan McClintock, Donghai Wu, Steven Slivken, Manijeh Razeghi Proc. SPIE 10540, Quantum Sensing and Nano Electronics and Photonics XV, 105400A-- January 26, 2018 ...[Visit Journal] Mid-infrared lasers, emitting in the spectral region of 3-12 μm that contain strong characteristic vibrational transitions of many important molecules, are highly desirable for spectroscopy sensing applications. High efficiency quantum cascade lasers have been demonstrated with up to watt-level output power in the mid-infrared region. However, the wide wavelength tuning, which is critical for spectroscopy applications, is still largely relying on incorporating external gratings, which have stability issues. Here, we demonstrate the development a monolithic, widely tunable quantum cascade laser source emitting between 6.1 and 9.2 μm through an on-chip integration of a sampled grating distributed feedback tunable laser array with a beam combiner. A compact tunable laser system was built to drive the individual lasers within the array and coordinate the driving of the laser array to produce desired wavelength. A broadband spectral measurement (520cm^-1) of methane shows excellent agreement with Fourier transform infrared spectrometer measurement. Further optimizations have led to high performance monolithic tunable QCLs with up to 65 mW output while delivering fundamental mode outputs. [reprint (PDF)]
17.	High power continuous operation of a widely tunable quantum cascade laser with an integrated amplifier S. Slivken, S. Sengupta, and M. Razeghi Applied Physics Letters 107, 251101-- December 21, 2015 ...[Visit Journal] Wide electrical tuning and high continuous output power is demonstrated from a single mode quantum cascade laser emitting at a wavelength near 4.8 μm. This is achieved in a space efficient manner by integrating an asymmetric sampled grating distributed feedback tunable laser with an optical amplifier. An initial demonstration of high peak power operation in pulsed mode is demonstrated first, with >5 W output over a 270 nm (113 cm⁻¹) spectral range. Refinement of the geometry leads to continuous operation with a single mode spectral coverage of 300 nm (120 cm⁻¹) and a maximum continuous power of 1.25 W. The output beam is shown to be nearly diffraction-limited, even at high amplifier current. [reprint (PDF)]
17.	Room temperature operation of In_xGa_1-xSb/InAs type-II quantum well infrared photodetectors grown by MOCVD D. H. Wu, Y. Y. Zhang, and M. Razeghi Applied Physics Letters 112, 111103-- March 14, 2018 ...[Visit Journal] We demonstrate room temperature operation of In_0.5Ga_0.5Sb/InAs type-II quantum well photodetectors on InAs substrate grown by metal-organic chemical vapor deposition. At 300 K, the detector exhibits a dark current density of 0.12 A/cm², peak responsivity of 0.72 A/W corresponding to a quantum efficiency of 23.3%, with calculated specific detectivity of 2.4×10⁹ cm.Hz^1/2/W at 3.81 μm. [reprint (PDF)]
17.	High-power, continuous-wave, phase-locked quantum cascade laser arrays emitting at 8 μm WENJIA ZHOU,QUAN-YONG LU,DONG-HAI WU, STEVEN SLIVKEN, AND MANIJEH RAZEGHI OPTICS EXPRESS 27, 15776-15785-- May 20, 2019 ...[Visit Journal] We report a room-temperature eight-element phase-locked quantum cascade laser array emitting at 8 μm with a high continuous-wave power of 8.2 W and wall plug efficiency of 9.5%. The laser array operates primarily via the in-phase supermode and has single-mode emission with a side-mode suppression ratio of ~20 dB. The quantum cascade laser active region is based on a high differential gain (8.7 cm/kA) and low voltage defect (90 meV) design. A record high wall plug efficiency of 20.4% is achieved from a low loss buried ridge type single-element Fabry-Perot laser operating in pulsed mode at 20 °C. [reprint (PDF)]
16.	High-performance bias-selectable dual-band mid-/long-wavelength infrared photodetectors and focal plane arrays based on InAs/GaSb Type-II superlattices M. Razeghi; A. Haddadi; A.M. Hoang; G. Chen; S. Ramezani-Darvish; P. Bijjam Proc. SPIE 8704, Infrared Technology and Applications XXXIX, 87040S (June 11, 2013)-- June 11, 2013 ...[Visit Journal] We report a bias selectable dual-band mid-wave infrared (MWIR) and long-wave infrared (LWIR) co-located detector with 3 μm active region thickness per channel that is highly selective and can perform under high operating temperatures for the MWIR band. Under back-side illumination, a temperature evolution study of the MWIR detector's electro-optical performance found the 300 K background-limit with 2π field-of-view to be achieved below operating temperatures of 160 K, at which the temperature's 50% cutoff wavelength was 5.2 μm. The measured current reached the system limit of 0.1 pA at 110 K for 30 μm pixel-sized diodes. At 77 K, where the LWIR channel operated with a 50% cutoff wavelength at 11.2 μm, an LWIR selectivity of ∼17% was achieved in the MWIR wave band between 3 and 4.7 μm, making the detector highly selective. [reprint (PDF)]
16.	Recent advances in IR semiconductor laser diodes and future trends M. Razeghi; Y. Bai; N. Bandyopadhyay; B. Gokden; Q.Y. Lu; S. Slivken Photonics Society Summer Topical Meeting Series, IEEE [6000041], pp. 55-56 (2011)-- July 18, 2011 ...[Visit Journal] The wall plug efficiency of the mid-infrared quantum cascade laser in room temperature continuous wave (cw) operation is brought to 21%, with a maximum output power of 5.1 W. Using a surface grating distributed feedback (DFB) approach, we demonstrated 2.4 W single mode output in room temperature cw operation. With a photonic crystal distributed feedback (PCDFB) design, we achieved single mode spectrum and close to diffraction limited far field with a room temperature high peak power of 34 W. [reprint (PDF)]
16.	4.5 mW Operation of AlGaN-based 267 nm Deep-Ultraviolet Light-Emitting Diodes A. Yasan, R. McClintock, K. Mayes, D. Shiell, L. Gautero, S.R. Darvish, P. Kung and M. Razeghi Applied Physics Letters, 83 (23)-- December 8, 2003 ...[Visit Journal] We demonstrate 4.5 mW output power from AlGaN-based single quantum well ultraviolet light-emitting diodes at a very short wavelength of 267 nm in pulsed operation mode. The output power in continuous-wave mode reaches a value of 165 µW at an injected current of 435 mA. The measurements were done on arrays of four devices flip chip bonded to AlN submounts for thermal management. [reprint (PDF)]

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