Epsilon-near-zero enhanced plasmonic Brewster transmission through subwavelength tapered metallic gratings

Recently, epsilon-near-zero (ENZ) materials have been employed to stimulate light funnelling enhancement through a subwavelength metallic channel. In this paper, we present a study of enhanced optical transmission through subwavelength metallic gratings deposited on ENZ material and gallium-arsenide (GaAs) substrate. We propose to carve periodically tapered slits on the metallic grating to enable the impedance matching at the entrance and exit faces and thus enhance the light transmission at the plasmonic Brewster angle. The optimal grating geometry provides around 80% average transmission over a broad bandwidth from 5 THz to 20 THz at the incident Brewster angle of 76°. Our study extends potential practical applications of ENZ materials for integrated photonics.