Microphotonic waveguide including core/cladding interface layer

A method for fabricating a waveguide comprising:

• forming a waveguide undercladding layer on a substrate;
• forming an amorphous hydrogenated silicon waveguide core on the undercladding layer;
• forming an interface layer comprising SiN on longitudinal sidewall surfaces of the waveguide core;
• and
• forming an upper cladding layer on a longitudinal top surface and on longitudinal sidewall surfaces of the waveguide core, over the interface layer wherein the waveguide interface layer is characterized by a thickness of between about 1 nm and about 100 nm.

A waveguide comprising:

• a hydrogen-doped polysilicon waveguide core having longitudinal sidewall surfaces, a longitudinal top surface, and a longitudinal bottom surface that is disposed on a substrate;
• an interface layer comprising SiN disposed on the longitudinal sidewall, bottom, and top surfaces of the waveguide core;
• and
• a waveguide cladding layer disposed on at least the waveguide core sidewall and top surfaces, over the interface layer wherein the waveguide interface layer is characterized by a thickness of between about 1 nm and about 100 nm.