Focal length switchable metalens based on vanadium dioxide.

A metalens is a flat lens that can control the phase of light so that dispersed light can be reconcentrated. This study devised a tunable metalens with a switchable focal length based on the phase transition properties of vanadium dioxide ( ). The unit structure comprises three layers from bottom to top: gold, polyimide, and two square resonant rings.

A dual functional tunable terahertz metamaterial absorber based on vanadium dioxide.

A dual-functional switchable metamaterial absorber (MMA) based on vanadium dioxide (VO), which achieves flexible switching between broadband absorption and four-band absorption by adjusting the VO conductivity, was proposed. The device has a broadband absorption function when VO is in the metal phase, and the conductivity is 3 × 10 S m. Numerical simulation shows that the absorption rate of the device reaches over 90% in the frequency range of 3.