Ultra‐High Transmission Broadband Tunable VO2 Optical Limiter

Abstract An optical limiter (OL) is a nonlinear device that protects sensitive photodetectors or human eyes from high‐intensity illumination. However, current OLs have low open‐state transmittance and a limited turndown ratio in some cases. In this study, first it is demonstrated that combining the insulator‐to‐metal transition (IMT) of vanadium dioxide (VO 2 ) with anti‐reflection layers can enable both high and broadband open‐state transmittance (>−0.9 dB at the peak wavelength) while preserving a large turndown ratio (>21.8 dB). Furthermore, optothermal simulation is conducted to analyze the performance of the VO 2 OL under ultrafast laser irradiation. The result reveals that IMT of the VO 2 OL occurs at 0.23 µs when the incident laser intensity is 90 kW cm −2 . These benefits offer a promising alternative to OLs in technologies ranging from sensor protection to human eye defense.