Multi-layer waveguide optical coupler

A method of using an optical coupler, comprising:

• receiving light in a light receiving end of an optical coupler, the optical coupler having a light output end opposite the light receiving end, and including:
• a plurality of waveguide core layers formed from a waveguide core material having a first index of refraction, said waveguide core layers being (i) arranged in a stacked relationship one over another, (ii) spaced apart one from another and (iii) extending from a light receiving end of the optical coupler longitudinally through the optical coupler toward a light output end of the optical coupler;
• and
• a cladding formed from a cladding material having a second index of refraction, said second index of refraction being less than the first index of refraction, said cladding material surrounding each of the plurality of waveguide core layers;
• wherein light propagating within outer ones of the plurality of waveguide core layers is directed toward an interior one of the plurality of waveguide core layers via evanescent coupling between adjacent ones of the plurality of waveguide core layers;
• and
• wherein the plurality of waveguide core layers comprises:
• a central waveguide core layer that extends from the light receiving end to the light output end of the optical coupler;
• a pair of outermost waveguide core layers arranged on opposite sides of the central waveguide core layer;
• and
• a pair of intermediate waveguide core layers arranged on opposite sides of the central waveguide core layer and interposed between the outermost waveguide core layers and the central waveguide core layer;
• and
• transmitting light out through the light output end.

An optical coupler, comprising:

• a plurality of waveguide core layers formed from a waveguide core material having a first index of refraction, said waveguide core layers being (i) stacked one over another, (ii) spaced apart one from another and (iii) extending from the light receiving end of the optical coupler longitudinally through the optical coupler toward the light output end of the optical coupler;
• and
• a cladding formed from a cladding material having a second index of refraction, said second index of refraction being less than the first index of refraction, said cladding material surrounding each of the plurality of waveguide core layers;
• wherein at least two of the waveguide core layers is a discontinuous waveguide core that is discontinuous along its longitudinal direction such that a second portion thereof is offset from a first portion thereof by a gap within which is disposed a portion of the cladding;
• and
• wherein the plurality of waveguide core layers comprises:
• a central waveguide core layer;
• a pair of outermost waveguide core layers arranged on opposite sides of the central waveguide core layer;
• and
• a pair of intermediate waveguide core layers arranged on opposite sides of the central waveguide core layer and interposed between the outermost waveguide core layers and the central waveguide core layer;
• and
• wherein the central waveguide core layer extends to the light output end of the optical coupler, while the pair of outermost waveguide core layers and the pair of intermediate waveguide core layers stop short of the light output end of the optical coupler.