Absorption recovery time reduction in InGaN/GaN quantum well saturable absorbers

Abstract

In this work, a simple method to reduce the absorption recovery time of the InGaN/GaN quantum well saturable absorber was demonstrated. The recovery time of the saturable absorber grown by metal organic chemical vapor deposition was effectively controlled by controlling the crystal quality. Transmission electron microscopy results showed that, for saturable absorbers with reduced GaN buffer thicknesses, increased dislocations were introduced into the quantum well regions. The degraded crystal quality would therefore cause an increased density of nonradiative recombination centers, which were responsible for the fast recovery of the absorption. In addition, with the as-grown thin GaN buffers, the severe interference-induced reflectivity fluctuations were successfully suppressed.