Tunable terahertz plasmonic filter based on a substrate of photo-induced phase-transition vanadium dioxide film

Abstract

A tunable terahertz (THz) filter is reported, which was based on surface plasmonic effects from a subwavelength copper hole array, and the tunability was made possible by a substrate of phase-transition vanadium dioxide (VO₂) film. The phase transition of the VO₂ film was induced by femtosecond laser pulses and the modulation depth of the THz pulse peak by the VO₂ film was measured by THz time-domain spectroscopy to be 80% under optimal fabrication conditions. The change of the conductivity of the substrate film could lead to a shift of the center resonance frequency from 1.33 to 0.92 THz, a relative shift of 30.8%. This tunable THz filter holds great promise for various applications.