Terahertz transmission properties of vanadium dioxide films deposited on gold grating structure with different periods

Vanadium dioxide (VO₂) is a typical thermal induced phase transition material, exhibiting a transition from metallic phase at high temperature to insulating phase at low temperature, which is also accompanied by a conductivity change of over several orders of magnitude. The transition property makes VO₂ prominent to achieve an effective degree of control of terahertz (THz) wave. In this paper, composite films consisting of metal grating with different periods and VO₂ film were prepared by polymer assisted deposition method. Although the conductivity change of VO₂ films deposited on gold grating structure across phase transition was declined to about two orders of magnitude, the amplitude modulation depth of THz of the composite films can still reach a high value. Furthermore, it was found that the THz modulation depth was related with the grating period. According to theoretical simulation, the fluctuation height of VO₂ films, caused by metal grating structure during growth, can be used to regulate THz wave. These results demonstrate an economic and unsophisticated method to fabricate VO₂ films with thickness fluctuation structure and then tune the THz waves. (paper)