Optical travelling-wave antenna with stopband closure through asymmetrical grating

Abstract

The technology described herein is generally directed towards an optical grating antenna (coupler) designed as a travelling wave or leaky wave antenna, based on laterally asymmetrical structural perturbations along the top (wire) of the antenna. In one implementation, the perturbations are protrusions in the form of nanopillar pairs distributed along the top of the antenna. The lateral asymmetry in the nanopillar segment pairs' distribution produces strong emissions in the broadside direction based on destructive interference of reflections resulting from the asymmetry, unlike conventional grating antennas with high reflections resulting in a stopband at broadside emission. The optical antenna, which can be implemented as a silicon-on-insulator waveguide, is suitable for linear-polarized emissions in the telecommunications infrared C-band, as well as in other applications including holography. Instead of laterally asymmetrical nanopillar pairs, other implementations can use structural perturbations of different geometries, including different shapes and/or notches/trenches in the antenna structure.

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