Design of near-infrared solid-state tunable Fabry-Perot filters based on VO₂/P4VP films

The significant refractive index change of VO₂ during phase transition makes it attractive for the design of optical switches and filters, but high absorption of VO₂ limits its development in the field of filter. In this paper, we firstly design near-infrared solid-state tunable/switchable single-/dual-band bandpass Fabry-Perot (F-P) filters based on VO₂/P4VP composite films using COMSOL software. The simulation results show that the single-passband tunable filter can achieve a continuous thermal tuning range of 19 nm at 1064 nm, the full width at half maxima (FWHM) is 28.8 nm, and the peak transmittance is >30%. On this basis, we simulated a tunable dual-band bandpass filter, the left peak can be heated to achieve a tuning range of 15 nm (945 nm), the right peak is 24 nm (1168 nm), the peak transmittances of both the two peaks are >35%. When boosting the VO₂ fraction, the continuous tunability of the above-mentioned single-/dual-band filters will be switchable due to the high absorption of VO₂, and then switchable single-/dual-band bandpass filters are designed. This work has guiding significance for the design of novel filter structures and optical tunable devices based on phase change materials such as VO₂ in the future.