An ultra-narrowband absorber with a dielectric-dielectric-metal structure based on guide-mode resonance

We report an ultra-narrowband absorber with a dielectric-dielectric-metal (DDM) tri-layer structure which is composed of a dielectric grating as the top layer, a dielectric spacer and a metal substrate. The simulation results show that, we can get an ultra-narrowband absorber with the absorption bandwidth less than 0.05 nm and the absorption rate more than 0.99 within an ultra-narrow angle for TE polarization (electric field is parallel to grating grooves). The results also show that the ultra-narrowband absorption for TE polarization is originated from guide-mode resonance and low power loss in the metal substrate. This ultra-narrowband absorber is a good candidate for application in coherent emission of light by thermal source.