We report on FP and DFB semiconductor lasers based on GaInAsSb/AlGaAsSb quantum wells, grown by molecular beam epitaxy. The devices were processed by wet etching or inductively coupled plasma process. Electron beam lithography was used to deposit a metal Bragg grating on each side of the laser ridge to fabricate DFB lasers. The devices all operate in the continuous wave regime at room temperature with a single frequency emission above 2.6 mum and good tuning properties, making them well adapted to tunable diode laser absorption spectroscopy.

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 (001) 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 2.65μm originating from the waveguide rather than from the wells. With an improved well/barrier periodicity, the second structure exhibited laser emission up to 243K at 2.93μm in the pulsed regime (200ns, 5kHz). In this case, the laser photons were effectively produced by the hole-well active region. A minimum threshold of about 12.8kA/cm2 at 80K combined with a T0 around 70K have been measured from this second structure.

We have made quantum wells laser diodes by Molecular Beam Epitaxy with emission wavelengths from 2.3 mu m to 3.1 mu m. With growing wavelength, threshold current densities increase almost exponentially. We obtained threshold values as low as 65 A/cm(2) at 2.3 mu m and 156 A/cm(2) at 2.62 mu m. At the same time, the valence-band offset decrease from 132 meV (at 2.3 mu m) to 78 meV (at 2.6 mu m). A threshold current density study shows that Auger effect is not the only responsible for the augmentation of J(th). The reduction of internal efficiency eta(i) has a greater impact on the increase of J(th). The diminution of the holes confinement is incriminated for the degradation of eta(i) with growing wavelength. Therefore, to improve J(th) at higher wavelengths another kind of barrier has to be utilized (for example, thanks to the use of the quinary material AlGaInAsSb).

We report on Fabry–Pérot semiconductor lasers and single frequency distributed feedback lasers based on GaInAsSb/AlGaAsSb quantum wells. The laser structures were grown by molecular beam epitaxy on GaSb substrates. The devices were etched either by wet process or by inductively coupled plasma (ICP) process. Electron-beam lithography was used to deposit a metal Bragg grating on each side of the laser ridge to fabricate the DFB lasers. The devices all operate in the continuous wave regime at room temperature with a single frequency emission above 2.6 μm and good tuning properties, making them well adapted to tunable diode laser absorption spectroscopy.

A report is presented on single frequency distributed feedback lasers based on GaInAsSb/AlGaAsSb quantum wells. The devices operate in the continuous-wave regime at room temperature with a single frequency emission above 2.6 mu m.

This work focuses on the fabrication and characterisation of DFB laser diodes operating around 2.6-2.65 μm. The laser structure is realized with a 1 μm-thick active region based on two Ga0.57In0.43As0.11Sb0.89 16 nm-thick compressively strained quantum wells embedded between a barrier and a waveguide made of Al0.30Ga0.70As0.03Sb0.97. The laser operate in the continuous-wave regime at room temperature with a threshold current of about 100 mA at 20°C and a characteristic temperature of 57 K. A single frequency emission is obtained between 2.6 μm and 2.65 μm with a side mode suppression ratio reaching 25 dB and a continuous tuning of 2 nm.

The operation ofelectrically-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-matchcd to GaSb. Laser operation was demonstrated from such structures up to 243 K at 2.93 mu m in the pulsed regime (200 ns, 5 kHz). A minimum threshold of about 12.8 kW/cm(2) combined with a To around 70 K have been measured.

We review here our results concerning laser diodes emitting at 2.38 mu m and 2.60 mu m. We present an original method allowing to determine the monomolecular, radiative and Auger recombination coefficients A, B and C, as well as the transparency carrier density N-tr, the internal loss alpha(i) and the gain coefficient g(, from the differential efficiency and the threshold current density obtained with different laser diodes. We show how these parameters can be used to optimize the number of quantum wells and explain the differences existing between laser diodes emitting at 2.38 and 2.60 mu m. At 2.38 mu m, we obtained a threshold current density of 76 A/cm(2) with a single quantum well laser diode and at 2.60 mu m, a J(th) of 152 A/cm(2) with a double quantum well laser diode. These threshold current densities can be compared favorably to the best reported values in the 0.85-3.0 mu m range.

Double quantum well laser diodes based on the GaInAsSb/AlGaAsSb system emitting at 2.61 μm in continuous-wave regime have been fabricated. In the pulsed regime for a 100 μm-wide 1600 μm-long device a record threshold current density of 76 A/cm2 per quantum well was obtained.

Strained triple-quantum-well (TQW) GaInAsSb/AlGaAsSb laser diodes were fabricated. Internal losses as low as 4 cm/sup -1/ and threshold current density per quantum well as low as 34 A/cm/sup 2/ for a 3 mm long-cavity were obtained.

Double quantum well laser diodes based on the GaInAsSb/AlGaAsSb system emitting at 2.61 µm in continuous-wave regime have been fabricated. In the pulsed regime for a 100 µm-wide 1600 µm-long device a record threshold current density of 76 A/cm2 per quantum well was obtained.

A GaInAsSb-AlGaAsSb large optical cavity triple-quantum-well structure was grown by molecular-beam epitaxy. Shallow mesa ridge-waveguide lasers with stripe width of 100 mum were fabricated and tested. An internal losses coefficient as low as 4 cm(-1) and a high internal quantum efficiency of 70% were obtained. In the pulsed regime at room temperature, the extrapolated threshold current densities for infinite cavity length is 78 A/cm(2). The threshold current density per quantum well is as low as 34 A/cm(2) for a 3-mm-long cavity.