Hybrid edge couplers with layers in multiple levels

A method of forming a structure for an edge coupler, the method comprising:

• forming a first waveguide core region on a first dielectric layer, wherein the first waveguide core region has an end surface, and the first waveguide core region is lengthwise tapered toward the end surface;
• forming a plurality of segments on the first dielectric layer, wherein the plurality of segments are positioned between the first waveguide core region and an edge of the first dielectric layer;
• forming a waveguide core including a section positioned over the first waveguide core region in an overlapping arrangement, wherein the waveguide core has an end surface, and the section is lengthwise tapered toward the end surface;
• forming a back-end-of-line stack over the waveguide core;
• removing a first portion of the back-end-of-line stack;
• and
• forming a second dielectric layer having an interface with a second portion of the back-end-of-line stack,
• wherein the second dielectric layer extends from the interface to the edge of the first dielectric layer, and the end surface of the waveguide core is coextensive with the interface.