Quasi-CW optical bistability in InSb at room temperature

We report the first observation of quasi-steady-state optical bistability in an InSb etalon at room temperature as a result of the generation of free carriers through two photon absorption of 10 μm radiation. Nonlinear tuning of the etalon through two free spectral ranges has been achieved, with bistability observed around the two cavity resonances. Switching from a low to high transmission state has been achieved in times less than 10 ns while switching in the opposite direction occurs within 50-100 ns. The experimental results have been successfully fitted to a numerical model of the device.