Fano-assisted LC-FP filtering for electrically tunable near-infrared imaging

A method for performing the near-infrared (NIR) imaging based on a key Fano-assisted liquid-crystal Fabry–Pérot (LC-FP) filtering tuned electrically is proposed. By integrating a pair of subwavelength Ge nano-grating upon each Al mirror shaped over the internal surface of the top and bottom substrates in a common LC-FP micro-cavity, a symmetry breaking is realized through effectively coupling the discrete chromatic dispersion modes with the traditional LC-FP lightfield continuum according to the traditional Lorentzian line shape. The lightfield distribution and phase response are analyzed to clarify the grating-assisted coupling mechanism in the micro-cavity. The spectral measurements in the NIR region demonstrate a nanometer-scaled resolution of the transmission radiations, which are basically consistent with the theoretical prediction. The NIR filtered imaging measurements show an obviously improved target visibility, which is supported by both the signal-to-noise ratio and the contrast-to-noise ratio evaluations.