Stimulated emission and lasing studies of wide gap II–VI compounds using optical excitation

Abstract

Stimulated emission and lasing effects of bulk ZnSe samples, grown by physical vapor-phase transport technique and MBE epilayers on GaAs substrates were investigated (using a 10-ns pulsed laser) in the frequency as well as in the time domain. For lasing studies, a laser cavity was formed by cleaving the sample’s two parallel facets with the cavity lengths of a few hundred microns. The cleaved edges were not subjected to reflective coatings. The lasing threshold densities were found to be surprisingly low; ~7 kW/cm2 for a sample with a cavity length of 300 μm. The longitudinal modes of the lasers were clearly resolved. Stimulated emission at both 10 and 300 K was observed. The stimulated emission was evidenced by the spectral narrowing of the emission peak, the highly superlinear dependence of the output signal on the pumping power density, and the narrowing of the temporal profile under high excitation. The gain values were measured by the variable excitation length method. The effect of the pumping photon energy on the stimulated emission at room temperature was investigated.