Low Threshold Strained Quantum Well Lasers at 1.5 Micron Wavelength

Abstract
InGaAs/InGaAsP multiple quantum well (MQW) lasers at 1.3-1.5 micron wavelength have yielded several advantages over bulk lasers at this wavelength range, such as low internal loss , high quantum efficiency, low threshold current operation and small linewidth enhancement factors [1-3]. There have been several reports predicting that further improvements are possible by employing strained layer quantum wells [4,5], as the effective mass of holes in the heavy hole sub-band of quantum well layers can be significantly reduced in the plane of the wells by compressive strain. This should result in lower threshold currents and other improvements of the laser parameters. Recently, the operation of InGaAs /InGaAsP strained layer MQW lasers at 1.5 micron was reported [6] with efficiency and output powers similar to the high values reported previously for unstrained MQW lasers. However, the expected reduction in threshold current and linewidth enhancement factor have not been observed.