Ultra-compact silicon waveguide-integrated Schottky photodetectors using perfect absorption from tapered metal nanobrick arrays

Abstract

We propose and numerically analyze an integrated metal-semiconductor Schottky photodetector consisting of a tapered metal nanoblock chain on a silicon ridge waveguide. The metal-semiconductor junctions allow broadband sub-bandgap photodetection through the internal photoemission effects. The tapered array structures with different block widths can gradually tailor the cut-off frequencies and group velocities of the tightly confined plasmonic modes for enhanced light absorption and suppressed reflection of the photonic mode in the silicon waveguide. As a result, according to our simulations, six metal nanobricks with a total device length of 830 nm can almost perfectly absorb the incident sub-bandgap light and subsequently generate photocurrents with a peak responsivity value of 0.125 A/W at 1550 mn We believe that the proposed design can provide a simple and viable solution for broadband and compact photodetection in the integrated silicon photonics platform. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement