Modulation of THz Radiation Based on Semiconductor–Metal Phase Transition in Vanadium Dioxide

In this paper, the method for THz radiation modulation based on the semiconductor–metal phase transition in vanadium dioxide (VO ₂ ) was explored. Thermal heating of a VO ₂ film on the silicon substrate above the metallic-state temperature resulted in the ~80% reduction of THz radiation transmission. For two-electrode VO ₂ film structures with millimeter-sized interelectrode gap, heating the film by means of electric current leads to the ~42% transmission reduction only. At the same time, due to the heating of the VO ₂ film substrate, a slow (seconds-running) cooling process and the film reverse transition to the semiconductor state occur. To increase the modulation frequency up to hundreds of kHz, it is proposed to create a structured system of separated micron-sized VO ₂ -elements instead of a continuous film, which allows for much faster cooling such elements, which was confirmed experimentally.