Planar waveguide optical isolator in thin silicon-on-isolator (SOI) structure

US7113676B2 · kind B2 · utility

Inventors

• David Piede · Allentown, US
• Margaret Ghiron · Allentown, US
• Prakash Gothoskar · Allentown, US
• Robert Keith Montgomery · Easton, US
• Vipulkumar Patel · Emmaus, US
• Kalpendu Shastri · Orefield, US
• Soham Pathak · Allentown, US
• Katherine A. Yanushefski · Emmaus, US
• Harvey Wagner · Royersford, US

Key dates

• Filing date: Dec 6, 2004
• Grant date: Sep 26, 2006
• Expiry date: Dec 6, 2024

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B6/4207
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A planar optical isolator is formed within the silicon surface layer of an SOI structure. A forward-directed signal is applied to an input waveguiding section of the isolator and thereafter propagates through a non-reciprocal waveguide coupling region into an output waveguide section. A rearward-directed signal enters via the output waveguide section and is thereafter coupled into the non-reciprocal waveguide structure, where the geometry of the structure functions to couple only a small amount of the reflected signal into the input waveguide section. In one embodiment, the non-reciprocal structure comprises an N-way directional coupler (with one output waveguide, one input waveguide and N−1 isolating waveguides). In another embodiment, the non-reciprocal structure comprises a waveguide expansion region including a tapered, mode-matching portion coupled to the output waveguide and an enlarged, non-mode matching portion coupled to the input waveguide such that a majority of a reflected signal will be mismatched with respect to the input waveguide section. By cascading a number of such planar SOI-based structures, increased isolation can be achieved—advantageously within a monolithic…