Broadband mid-infrared optical limiter based on vanadium dioxide phase transition

Optical limiters (OLs) are necessary devices for the protection of sensitive photo-detectors from high-intensity laser irradiation. However, current OLs based on vanadium dioxide (VO 2 ) phase transition show a limited wavelength protection bandwidth, insufficient transmittance in the low-temperature phase, and an open-limited turndown ratio (infrared switching rate). Therefore, this study presented a continuously tunable 3000–5000 nm mid-infrared broadband VO 2 -based OL by combining the insulator-to-metal transition of VO 2 with a multi-layer thin film. And the optical-thermal properties of the OL were analyzed using the finite element method (FEM). The results revealed that the OL represented excellent laser protection performance in the 3000–5000 nm broadband wavelength region such as a low-temperature phase transmittance higher than 70%, an infrared switching rate of 98%, and the broad working bandwidth of more than 3000 nm.