Angle-insensitive Bifunctional Resonator Based on Periodic Structure

An angle-insensitive bifunctional resonator composed of a compound silver grating is proposed. The resonator exhibits different response characteristics for TE and TM polarization, thus enabling two functions, corresponding to high-sensitivity sensor and low Q-factor absorber. For TE polarization, the Q-factor, refractive index sensitivity, and figure of merit of the resonator can reach 283.4, 2577.6 nm/RIU, and 181.5 RIU-1, respectively, due to the excitation of cavity mode resonance. For TM polarization, the resonator can be regarded as an absorber with high absorptivity (> 97%) based on magnetic resonance. This simple structure provides a good paradigm for designing high-performance multi-functional devices.