High Q Polarization Independent Guided-Mode Resonance Filter With “Doubly Periodic” Etched Ta$_2$O$_5$ Bidimensional Grating

We experimentally demonstrate, by etching a “doubly periodic” pattern in a high-index material (Ta
₂
O
₅
), that guided-mode resonance filters can exhibit polarization independent peaks with a
Q
factor of 5600. Beyond this promising result, complementary characterizations give us some leads to rectify the energy repartition between reflection, transmission, and losses.