Heterostructure-based optical absorbers

摘要

We have fabricated optical absorbers based on heterostructures composed of thick metallic films and truncated all-dielectric photonic crystals. Under the tunneling mechanism, the light can enter the heterostructure without reflection and is greatly absorbed due to the strong local-field enhancement in the metallic film. With the increase in the thickness of the metal, the absorbance will tend to unity. Experiments, in good agreement with the simulations, demonstrate a maximum of absorbance close to 98%. Possible methods to realize a wide-angle or/and wideband absorption are also given.