Theoretical design and investigation of VO2-based tunable broadband terahertz metasurface absorber

Terahertz devices is promising in the development of next-generation infrared photodetectors. However, the performances of photodetectors are largely limited by their poor light absorption and small detection range. Here, we designed a vanadium dioxide (VO2) based tunable broadband terahertz (THz) metasurface absorber (VO2-BTMA) for a wider tunable broadband detection range. The results show that the VO2- BTMA is able to maintain more than 90% absorption in the range of 2.21–5.64 THz with an ultra-wide bandwidth of 3.43 THz. When the absorption peaks are at 2.607 THz and 5.064 THz, the absorption rates of VO2- BTMA devices reaches 96.8% and 96.4% respectively. Meanwhile, we found that the conductivity of VO2 can be controlled by changing the temperature, thus affecting the absorption rate of the device and achieving tunability. When the incident angle of terahertz wave increases from 0° to 50°, the absorber can still maintain 80% of the absorption rate, and the absorber has excellent stability.