Turning grating device for emission of arbitrary optical beam profiles from waveguides into two-dimensional space

A method of fabricating a turning grating coupler device, the method comprising:

• forming a substrate layer comprising a bottom cladding layer that includes a first material having a first refractive index;
• depositing a core layer over the bottom cladding layer, the core layer including a second material having a second refractive index that is greater than the first refractive index;
• forming a waveguide layer from the core layer;
• and
• forming a grating structure and an output slab from the waveguide layer;
• wherein the grating structure is formed with an array of sub-waveguides that are substantially parallel to each other along a first propagation direction, wherein each of the sub-waveguides is formed with opposing sidewalls, and a width of each sub-waveguide is defined by a distance between the opposing sidewalls, wherein the width of each sub-waveguide is varied such that each of the opposing sidewalls has a periodic structure that produces a sidewall periodic modulation that is out of phase with respective sidewall periodic modulations of adjacent neighboring sub-waveguides;
• wherein the output slab is formed so as to adjoin with the grating structure such that the optical slab is in optical communication with the grating structure.

An optical device, comprising:

• an integrated photonics chip;
• an input waveguide on the photonics chip;
• and
• a turning grating coupler on the photonics chip and optically coupled to the input waveguide, the turning grating coupler including a waveguide core layer that comprises:
• a grating structure comprising an array of sub-waveguides that are substantially parallel to each other along a first propagation direction, wherein each of the sub-waveguides has opposing sidewalls, and a width of each sub-waveguide is defined by a distance between the opposing sidewalls, wherein the width of each sub-waveguide is varied such that each of the opposing sidewalls has a periodic structure that produces a sidewall periodic modulation that is out of phase with respective sidewall periodic modulations of adjacent neighboring sub-waveguides;
• and
• an output slab that adjoins with the grating structure such that the optical slab is in optical communication with the grating structure;
• wherein the input waveguide is configured to receive a light beam from a light source and direct the light beam into the grating structure in the first propagation direction, wherein the sub-waveguides are configured to diffract the light beam into the output slab in a second propagation direction that is substantially perpendicular to the first propagation direction.