Optical Spectroscopic and Gain Properties of II-VI Heterostructures for Semiconductor Disk Laser Application*

Semiconductor Disk Lasers (SDLs) operating in the 480-630 nm spectral range are of interest for a variety of applications. We report on the synthesis, structural properties, as well as optical spectroscopic and gain characteristics of ZnCdSe/ZnCdMgSe multiple quantum well (MQW) structures grown lattice matched on InP substrates using molecular beam epitaxy (MBE) for potential SDL operation in the green-yellow spectral range. Linear 2θ-ω x-ray diffraction scans revealed excellent crystalline quality of the samples. Under steady-state and low-power pulsed excitations bright photoluminescence (PL) was observed with peak around 565 nm and a room-temperature lifetime of ~ 1 ns. Under more intense ultrashort pulsed excitation, time-resolved PL measurement with a streak camera revealed stimulated emission at longer wavelengths, spectral narrowing and lifetime shortening to ~ 100 ps. For optical gain measurements, the InP substrate was removed by selective chemical etching and MQW structures were placed on a transparent sapphire plate. Optical gain characteristics were studied using an excite-and-probe scheme. The gain spectra correlate with stimulated emission spectra.