Electron-hole—pair generation and hysteresis in semiconductors

We consider the electron-hole—pair generation and the resulting free-carrier-density buildup in a semiconductor irradiated with laser beams whose frequencies are below the band gap. Using a simple model, we show that the free-carrier density may exhibit hysteresis and that when placed in a cavity, the semiconductor causes optical multistability at relatively low input cw intensities. For InSb the model predicts hysteresis at or above ∼ 100 W / ${\mathrm{cm}}^2$.