Emission Properties of 6.7 Micron Vertical-Emitting Microcavity Lasers Operating in Continuous-Wave Mode

The emission properties of lead salt continuous-wave (cw) vertical-cavity surface-emitting lasers for the mid-infrared are presented. The structures, based on high-finesse microcavities containing PbSe as active medium, show optically pumped cw laser emission up to temperatures of 100 K at a long wavelength of 6.7 mum. Stimulated emission with a very narrow beam divergence below 1 deg and a large temperature tuning range of 70 nm is found. The measured line width of the laser emission is only 0.6 nm limited by the spectrometer resolution with a strong narrowing with respect to the line width of the sub-threshold signal. The sharp laser threshold is at a low pump power of 67 W/cm2 and the observed cw output power amounts up to 1.2 mW at 85 K with a conversion efficiency of 0.5 %.