Low-threshold optically pumped λ=4.4 μm vertical-cavity surface-emitting laser with a PbSe quantum-well active region

We report pulsed emission from an optically pumped lead-salt vertical-cavity surface-emitting laser with a PbSe/PbSrSe quantum-well active region. The lasing wavelength of $\text{λ=4.44\hspace{0.05em}μ}\mathrm{m}$ is nearly constant over the temperature range 200–280 K, and the threshold is only 10.5 kW/cm² at 260 K, where the gain peak and cavity mode are in resonance. Over 330 mW of peak power is emitted at 260 K, into a circular beam whose divergence angle increases with pump intensity.