Tunable and Polarization-Independent Wedged Resonance Filter With 2D Crossed Grating

In this letter, a tunable and polarization-independent guided-mode resonance filter that has two-dimensional crossed grating on a wedged waveguide layer of Ta
₂
O
₅
is fabricated and analysed for the communication band. The wedged waveguide layer is etched by the ion beam etching technique with a triangle-shaped mask, and the two-dimensional grating is made by holographic exposure technique. The measured spectra show that the filter can realize the property of polarization-independence at normal incidence. By the thickness gradient of the wedged layer, the filter is tunable in a range of 1599.9-1621.5 nm over a distance of 9 mm.