Method for Production of Optical Waveguides and Coupling and Devices Made from the Same

A method for producing a high-refractive index contrast and low loss optical waveguide, the method comprising the steps of:

• depositing or growing a low refractive index cladding layer on top of a silicon base substrate;
• depositing a high refractive index material layer on top of the low refractive index cladding layer to form a slab core region;
• depositing an optically-transparent layer on top of the slab core region;
• depositing or growing a refractory metal layer on top of the optically-transparent layer;
• forming a trench in a top diffusion barrier layer deposited on the refractory metal layer, wherein the trench has an open surface for the refractory metal layer;
• oxidizing the open surface by exposing the open surface of the refractory metal layer to high-temperature ambient oxygen, wherein the open surface of the refractory metal layer subsequently forms an oxidized refractory metal region, and wherein other parts of the refractory metal layer still covered under the top diffusion layer remain unchanged as a non-oxidized refractory metal region;
• removing the top diffusion barrier layer using one or more chemical etching agents;
• removing the non-oxidized refractory metal region by using a dry-etching tool with high-etch selectivity to preserve the oxidized refractory metal region;
• and
• depositing a top cladding layer made of a second low refractive index material to encapsulate the oxidized refractory metal region.