Analysis of 6-nm AlGaAs SQW Low-Confinement Laser Structures for Very High-Power Operation

Abstract — This paper reports experimental results on sin-gle quantum-well separate confinement heterostructures (SQW SCH) with low-confinement factor, designed for very high-power operation. The maximum power output for AR/HR coated 3-mm-long devices, measured in very short pulsed conditions (100 ns/1 kHz), from 10-m-wide stripes was as high as 6.4 W before catastrophical optical degradation. If scaled to continuous-wave (CW) conditions, this value would be 800–1100 mW, which would mean a factor of 2–2.7 times more than reported for the best devices with normal design for threshold minimization. The absorption coefficient for the symmetrical structure is as low as 1.1 cm1, in spite of the low trapping efficiency of carriers in the quantum well (QW). The maximum differential efficiency is 40 % (both faces, uncoated devices) for symmetrical structure and 33 % for the asymmetrical one (all measurements in pulsed conditions). Threshold current densities were 800 A/cm2 for 5-mm-long devices in the symmetrical case and 2200 A/cm2 in the asymmetrical one. The effects of inefficient carrier trapping in the QW on the threshold current densities and differential efficiency are discussed. Index Terms—Gallium materials/devices, injection lasers, op-toelectronic devices, quantum-well devices, semiconductor lasers. I