Brewster angle for plasmonic gratings

In this paper, we analyze the transmission properties of metallic gratings at optical frequencies. In particular, we show that an inherently ultra-broadband tunneling mechanism may be obtained based on impedance matching between the guided modes supported by ultranarrow slits and freespace TM plane waves impinging at an oblique angle. This phenomenon is the analogous of the well-known Brewster transmission for dielectric slabs, but it is obtained here for mostly opaque metallic gratings. We focus on the transmission of short pulses in time domain through such grating, showing that broadband signals may be transmitted with weak distortion, very different from typical extraordinary optical transmission based on resonant phenomena.