Tuning the functionality of VO2-based thermal switches with TMDC monolayers and thin layer of gold

Photonic switches are mostly advantageous over mechanical ones due to their fast response, high efficiency, and tunability. Phase change materials (PCMs) whose optical characteristics change under external stimuli, are widely used in the context of photonic switches. One of the well-known PCMs is VO2, which undergoes a dielectric to metal phase change with exceeding the temperature beyond 68(degrees)C. The switch structures that we investigate in this paper, consist of VO2 as the switching material, silica as the substrate, WS2 which is a transition metal dichalcogenide, and a thin layer of gold (Au). Apart from the decisive role of Au in switch operation in reflective mode, we show that both Au thickness and the number of WS(2 )layers can tune both the reflection change and bandwidth of our designed switch. Maximum change of reflection value of 9% with a bandwidth of 0.24 mu m is achieved by insertion and increasing the WS2 layers to 20 when the Au thickness is 40 mu nm. While changing the Au thickness from 10 nm to 100 mu nm gives more flexibility in the reflection amplitude switching of our designed switch with a maximum shift of 17% when the number of WS2 layers is 10. With sweeping over both WS2 layers and Au thickness, we achieved a significant switching bandwidth of 0.62 mu m. Our designed switch paves a new way in designing miniaturized photothermal switches with high efficiency and tunability.