Continuous, high-power operation of a strained InGaAs/AlGaAs quantum well laser

Abstract

Continuous wave (cw), high-power operation of a strained In0.2Ga0.8As/ AlGaAs quantum well laser, grown by atmospheric pressure organometallic vapor phase epitaxy, is reported. The laser active region consists of a single 70 Å In0.2Ga0.8As/Al0.2Ga0.8As quantum well, with optical confinement provided by a graded index separate confinement heterostructure. The threshold current density and differential quantum efficiency of a 90 μm×600 μm stripe with uncoated facets are ∼200 A/cm2 and 46%, respectively. Lasing wavelength is ∼930 nm, and the cw single ended power versus current characteristic is linear up to 250 mW (1 A current). In the short-cavity (<300 μm) regime, these devices have high thresholds and have been observed to lase at shorter wavelength, presumably due to a saturation of gain at the lowest energy transition. The characteristic temperature is 150 K and decreases somewhat with cavity length. This suggests that some nonradiative process, most likely Auger recombination, contributes significantly to quantum well gain saturation.