Nanoresonator Enabled Ultrafast All‐optical Terahertz Switching Based on Vanadium Dioxide Thin Film

We demonstrate nanoresonator enabled ultrafast all‐optical switching of terahertz transmission based on phase transition of vanadium dioxide (VO2) thin film. Nanoresonators, nm‐width slot antenna patterns on the gold layer, are fabricated on the VO2 films. Without nanoresonators, THz wave shows negligible change through bare VO2 film even though optical pumping exists, while about 20 percents switching ratio is clearly seen with nanoresonator patterns on the VO2. The switching time is in a few hundreds femtosecond time scales.