[Show abstract][Hide abstract] ABSTRACT: This paper is dedicated to the study of electrical and optical properties of four different doped 21.5 pairs AlAsSb/GaSb distributed Bragg reflectors lattice-matched to GaSb and designed for the fabrication of electrically pumped VCSELs emitting around 2.3 µm. Three different doping profiles have been carried out: n-bulk doping, n-delta doping and p-bulk doping. An n-type bulk doped Bragg mirror with step composition at GaSb/AlAsSb interfaces was also tested. The n-type bulk doped sample with sharp interfaces exhibited the best electrical properties, a voltage drop per pair of 25 mV and a specific resistance of 1 × 10−4 Ω cm2 at 1 kA cm−2. Moreover, optical losses as low as 5–10 cm−1 have been measured for n-type doped mirrors.
Semiconductor Science and Technology 09/2007; 22(10):1140. · 1.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The growth by molecular-beam epitaxy of novel electrically pumped type-II multi-quantum well (MQW) Sb-based laser diodes in which only the holes are quantum confined was studied. These laser structures were fabricated on (0 0 1) GaSb substrates. In the MQW region, radiative recombinations originate from InGaSb hole wells embedded in InGaAsSb barriers lattice matched to GaSb. Two different laser structures were developed. The first one exhibited a well/barrier periodicity that was too short, which led to a laser emission near 2.65 μm originating from the waveguide rather than from the wells. With an improved well/barrier periodicity, the second structure exhibited laser emission up to 243 K at 2.93 μm in the pulsed regime (200 ns, 5 kHz). In this case, the laser photons were effectively produced by the hole-well active region. A minimum threshold of about 12.8 kA/cm2 at 80 K combined with a T0 around 70 K have been measured from this second structure.
Journal of Crystal Growth 01/2007; · 1.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The operation of electrically-pumped type-II Sb-based laser diodes in which only the holes are quantum confined is reported. These laser structures were fabricated by molecular beam epitaxy on (001) GaSb substrates. In the multi-quantum well region, radiative recombinations originate from InGaSb hole wells embedded in InGaAsSb barriers lattice-matched to GaSb. Laser operation was demonstrated from such structures up to 243 K at 2.93 mum in the pulsed regime (200 ns, 5 kHz). A minimum threshold of about 12.8 kW/cm<sup>2</sup> combined with a T<sub>0</sub> around 70 K have been measured
[Show abstract][Hide abstract] ABSTRACT: Diode lasers emitting at 2.26 μm, based on the InGaAsSb-AlGaAsSb materials system, are reported. These devices exhibit high internal quantum efficiency of 78% and low threshold current density of 184.5 A/cm<sup>2</sup> for a 2-mm-long cavity. Output power up to 700 mW (≈550 mW) has been obtained at 280 K (300 K) in continuous-wave operation with 100 μm×1 mm lasers. These devices have been coated with an antireflection on the output facet and are mounted epilayer down on a copper block. The working temperature was maintained by a thermoelectric Peltier cooling element.
[Show abstract][Hide abstract] ABSTRACT: First investigations of photoacoustic (PA) spectroscopy (PAS) of methane using an antimonide semiconductor laser are reported. The laser fabrication is made in two steps. The structure is firstly grown by molecular beam epitaxy, then a metallic distributed-feedback (DFB) grating is processed. The laser operates at 2371.6nm in continuous wave and at room temperature. It demonstrates single-mode emission with typical tuning coefficients of 0.04nmmA−1 and 0.2nmK−1. PA detection of methane was performed by coupling this laser into a radial PA cell. A detection limit of 20ppm has been achieved in a preliminary configuration that was not optimised for the laser characteristics.
[Show abstract][Hide abstract] ABSTRACT: We report on low-threshold high-power quantum well diode lasers emitting near 2.3 µm based on the GaInAsSb/AlGaAsSb system. The threshold current density per quantum well is as low as 63 A cm−2. A maximum output power of 540 mW at 293 K in the continuous wave regime has been achieved.
Semiconductor Science and Technology 11/2003; 19(2):260. · 1.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The wavelength range between 2 and 5 μm is of main interest for molecular spectroscopy and environmental monitoring. The 2.2-2.3 μm spectral region is a window for water vapor and CO<sub>2</sub> absorption while absorption lines of some atmospheric pollutants are very strong. One of the most sensitive techniques for selective gas analysis is tunable diode laser absorption spectroscopy (TDLAS). To reduce the cost and dimensions of the equipment, single frequency diode lasers and detectors operating in continuous wave (CW) regime at room temperature (RT) or above are required in this spectral range. In this contribution we summarize the results obtained in the development of 6.1 angstrom semiconductors diode lasers and their applications for trace gas detection. The laser structures were grown by molecular beam epitaxy on GaSb substrates. To estimate the spectral quality of the laser, emission mode maps of the lasers have been performed using a Fabry-Perot interferometer or directly absorption lines of gases of interest. We present some results on TDLAS of methane, carbon monoxide, carbon dioxide, and HF in trace concentrations, obtained with the GaSb diode lasers used in the CW regime at temperatures up to 800°C.
Lasers and Electro-Optics Society, 2002. LEOS 2002. The 15th Annual Meeting of the IEEE; 12/2002
[Show abstract][Hide abstract] ABSTRACT: Widely tunable GaInAsSb/AlGaAsSb quantum well (QW) lasers have been grown by molecular beam epitaxy on GaSb substrates. Their emission wavelength, from 2.0 to 2.5 microm, make them suitable for the detection of many gas species in the wavelength range which corresponds to an atmospheric transmission window. Using these devices an experimental setup for open path gas detection has been developed.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 10/2002; 58(11):2405-12. · 1.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have grown semiconductor lasers by molecular beam epitaxy (MBE) on  oriented GaSb:Te substrates. An 80% internal quantum efficiency was deduced from measurements of the external quantum efficiency versus cavity length. Internal losses as low as 7 cm-1 have been found. The system is able to reach threshold current densities as low as 63 A/cm2 per well for a cavity length of 1200 μm. This is, to our knowledge, the best reported value at 2.26 μm.
Conference Proceedings - International Conference on Indium Phosphide and Related Materials 01/2002;
[Show abstract][Hide abstract] ABSTRACT: Results of investigation of the multiple-quantum well vertical-cavity laser structure including non-uniformity of laser, diffusion processes, dynamical and thermal effects and transparent cavity modes are presented. Obtained results allow optimising lasing properties by changing geometrical parameters
Laser and Fiber-Optical Networks Modeling, 2001. Proceedings of LFNM 2001. 3rd International Workshop on; 02/2001
[Show abstract][Hide abstract] ABSTRACT: One of the main concerns in environmental issues is the accumulation of pollutant gases in the atmosphere. This gives ris to a need for convenient ways of detecting these gases. In this paper we review some fundamentals of a technique called ‘tunabl diode laser absorption spectroscopy’, which is suitable for making a portable gas analyser. We focus on the 2.2–2.4 μm rang which corresponds both to a transparency window in the atmosphere and to high absorption bands of the main pollutant gases.
We present two GaInAsSb/AlGaAsSb laser diodes which meet well the requirements for a portable gas analyser: a laser diod emitting at 2.38 μm exhibiting a monomode emission (side–mode suppression ratio 30 dB) and a laser diode emitting at 2.3 μm able to operate continuous wave up to 140°C. Thanks to these diodes we designed a set–up for gas detection using the tunabl diode laser absorption spectroscopy technique. We have reached a sensitivity as good as 1 ppm for CH4 at atmospheric pressure. Finally, we present a promising technique called ‘intra cavity laser absorption spectroscopy’ makin use of a new device, the ‘vertical external cavity surface emitting laser’, which may allow us to increase sensitivity b a factor of 105.
Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences 01/2001; 359(1780):581-597. · 2.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Summary form only. The wavelength range between 2.2 and 2.4 μm are of great interest for molecular spectroscopy and environmental monitoring. Tunable diode laser absorption spectroscopy is one of the most accurate techniques for gas analysis and to reduce the cost of the equipment diode lasers operating in continuous wave (cw) regime above room temperature (RT) are required. In this contribution we present single mode GaInSbAs-GaAlSbAs QW lasers operating in cw regime up to 130°C
[Show abstract][Hide abstract] ABSTRACT: Narrow ridge 5 μm-wide GaInSbAs/GaAlSbAs quantum well (QW)
lasers emitting in the continuous wave (CW) regime at temperatures up to
130°C have been fabricated. The CW threshold current varied between
20 and 35 mA at room temperature (RT). The lasers operated in the
fundamental spatial mode and exhibited single longitudinal mode emission
over a wide range of CW operation conditions. The emission wavelength
increased from 2.26 μm at RT up to 2.43 μm at 124°C. The CW
output optical power reached 45 mW/facet at 22°C and exceeded 10
mW/facet at 100°C
[Show abstract][Hide abstract] ABSTRACT: Narrow ridge GaInSbAs/GaSb type-II QW lasers emitting at 2.37-2.4 µm have been fabricated. The lasers operated in the cw regime at room temperature with the output optical power up to 20 mW/facet. The internal quantum efficiency of the lasers was found to be 89% and the power efficiency reached 20%. The lasers emitted in the fundamental spatial mode and exhibited single frequency operation in a large range of currents and temperatures. The emission wavelength could be continuously tuned by current over 0.7-1.2 nm. The single longitudinal mode behaviour was explained by the photorefractive effect due to DX centres in the Te-doped GaAlSbAs cladding layer acting as a saturable absorber.
Semiconductor Science and Technology 03/2000; 15(4):390. · 1.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: There is a need for low-cost and portable equipment. The exigency in terms of the sensitivity lies around the 1 ppm level. Tunable diode laser spectroscopy (TDLAS) appears to be the best candidate to fulfill these requirements. To be performed in good conditions TDLAS needs the laser to be operated in continuous mode. Unfortunately there is presently no semiconductor laser able to operate in cw mode beyond 2.7 μm at room temperature. We try to overcome this problem
Laser and Fiber-Optical Networks Modeling, 2000. Proceedings of LFNM 2000. 2nd International Workshop on; 02/2000
[Show abstract][Hide abstract] ABSTRACT: Summary form only given. Narrow ridge GaInSbAs/GaAlSbAs strained quantum well lasers have been fabricated by molecular beam epitaxy. At room temperature (RT) the lasers had threshold currents in the range of 20-40 mA and emitted up to 40 mW/facet of optical power at 2.25-2.28 μm. They operated in the fundamental spatial mode and exhibited single frequency emission with the side longitudinal mode suppression reaching 20 dB in a large range of currents. The lasers operated in continuous wave (cw) regime up to 130°C. We were able to tune the emission wavelength in a very large range of 0.18 μm using a resistance heater instead of a Peltier cooler