Optical coupler with forked grating structure

Abstract

A device and system for coupling light into and out of a photonic integrated circuit. The forked grating coupler device applies a forked grating structure to the design of the diffracting lines in an integrated optics grating coupler to make the device compatible with vortex light beams to or from free space, bulk optics, or special optical fiber that can propagate vortex modes. These diffracting lines, which can be grooves, or ridges, or a photonic metamaterial discontinuity arranged in a continuous or intermittent curve, follow the forked diffraction pattern lobes over a two-dimensional surface. The resulting device can therefore absorb or radiate a vortex beam mode at near-normal incidence to a PIC and transform that vortex mode to a transverse electric (TE) or transverse magnetic (TM) waveguide mode traveling along a slab or strip optical waveguide parallel to the surface of the IC.

Dependencies are inferred from the claim text.