Fast amplitude modulation up to 1.5 GHz of mid-IR free-space beams at room-temperature

Applications relying on mid-infrared radiation (lambda similar to 3-30 mu m) have progressed at a very rapid pace in recent years, stimulated by scientific and technological breakthroughs like mid-infrared cameras and quantum cascade lasers. On the other side, standalone and broadband devices allowing control of the beam amplitude and/or phase at ultra-fast rates (GHz or more) are still missing. Here we show a free-space amplitude modulator for mid-infrared radiation (lambda similar to 10 mu m) that can operate at room temperature up to at least 1.5 GHz (-3dB cutoff at similar to 750 MHz). The device relies on a semiconductor heterostructure enclosed in a judiciously designed metal-metal optical resonator. At zero bias, it operates in the strong light-matter coupling regime up to 300 K. By applying an appropriate bias, the device transitions towards the weak-coupling regime. The large change in reflectance is exploited to modulate the intensity of a mid-infrared continuous-wave laser up to 1.5 GHz.

Automated summary

Applications utilizing mid-infrared radiation have advanced rapidly in recent years due to breakthroughs like mid-infrared cameras and quantum cascade lasers. However, standalone devices capable of controlling beam amplitude and/or phase at ultra-fast rates are still lacking. A free-space amplitude modulator for mid-infrared radiation has been demonstrated, operating at room temperature up to 1.5 GHz.