Dual-mode selectable tunable F-P filter with wide wavelength moving range in LWIR based on piezoelectric stack

In infrared hyperspectral detection, filter wheels are commonly used as precision spectroscopic components, which are limited by large volume, mechanical, and fixed spectral channels. Micro-electro-mechanical systems (MEMS) tunable filters have broad application prospects. We present a voltage piezoelectric-driven actively tunable Fabry-Pérot (F-P) filter working at long-wave infrared range 8 to 12 μm. Compared with conventional voltage-driven tunable filters, the proposed device achieves a centimeter-scale effective aperture by leveraging piezoelectric stack actuators. The filter exhibits excellent tunable linear gradient filtering performance by controlling the expansion movement of the piezoelectric stack separately, which provides a tunable F-P filter with two selectable modes. Experimental results demonstrate that in the static mode (without bias voltage), the transmission peak can be spatially tuned from 8.36 to 10.43 μm across the filtering area. Under dynamic actuation, the transmission peak is electrically tuned from 8.44 to 9.13 μm. The large-sized tunable filter we obtained can be integrated with a large-scale array infrared focal plane array detector, providing key optical components for the development of new-generation spectral detecting chips.