Self-Excited Free-Standing VO2 Film for Infrared Optical Limiter

Effective optical limiters (OLs) are necessary devices for the protection of various sensitive photo-detectors, cameras, infrared sensors, or even the human eyes once encountering unexpected high-intensity illumination or laser blinding attacks. Vanadium dioxide (VO2) shows pronounced infrared switching behavior across the phase transition, which is considered as an idea optical limiter for broad-band infrared laser protection. However, the self-adapting optical limiter function based on VO2 is quite difficult to realize since the open-state absorptance of the VO2 layer is always very low, which makes the laser irradiation cannot trigger the phase transition quickly. In the current study, a self-excited VO2 infrared optical limiter is proposed, which is integrated by a transferred VO2 layer, InGaAs micro/nano wires, and a local heater. Based on the"optical response-electric heating" strategy, the phase transition of VO2 layer can be quickly triggered once the incident laser beam intensity exceeds the pre-set threshold value. In addition, this integrated device has an excellent switching ratio, flexible controllability, and stability. This work achieves a practical VO2 optical limiter device and provides a promising strategy for developing VO2-based integrated multifunctional devices in the future.