High-efficiency and low-threshold InGaAs/AlGaAs quantum-well lasers

Abstract

High‐efficiency and low‐threshold InGaAs/AlGaAs quantum‐well laser structures have been grown by molecular beam epitaxy. Material characterization was performed on polyimide‐planarized ridge‐waveguide lasers. The measured material gain data are compared to theoretical calculations that include the valence‐band mixing effects. Total injection current densities of 84 and 60 A/cm² have been measured from 50‐μm‐wide laser diodes with cavity lengths of 2850 μm (from a double‐quantum‐well sample) and 1770 μm (from a single‐well sample), respectively. Moreover, we have also obtained a cw threshold current as low as 2.1 mA from a 1.7‐μm‐wide and 140‐μm‐long as‐cleaved ridge‐waveguide device. In addition, the lateral current leakage for the double‐quantum‐well sample is found to be twice that of the single‐well one.