Patent ID: 6580850
Filing Date: 2003-06-17
Classification: G02B,H01S

Abstract:
An optical waveguide mode transformer comprising:a substrate supporting an optical waveguide structure including a high refractive index core layer disposed between cladding material having a lower refractive index, said waveguide structure extending along a substrate surface, said core layer including an upstanding ridge on said core layer and spaced from opposite lateral edges of said core layer, said core layer including an input waveguide section coupled by an intermediate waveguide section to an output waveguide section, said intermediate waveguide section including a tapered region of said core layer ridge; said input waveguide section having a wide core layer ridge to accept a multimode light input including a fundamental mode, said output waveguide section including a narrow output end core layer ridge region to support propagation of single mode light output in said fundamental mode, said tapered region of the core layer ridge having a taper length to effect an adiabatic intensity transfer of said fundamental mode light from said input waveguide section to said output waveguide section while suppressing other modes of said multimode light input; and wherein said output waveguide section includes a narrow output region comprising a narrow core layer ridge portion preceded by a double-tapered core layer ridge region functional initially to expand and then contract the width of the fundamental mode light received from said intermediate waveguide section, said narrow output region supporting single mode propagation of said fundamental mode light; and in said output waveguide section, said core layer underlying said ridge is separated from opposite outer edge margin areas of said core layer by interposed cladding material to define a tapered interface between said outer edge margins of said core layer and said cladding material, said tapered interface increasing in width towards the output end surface of said optical waveguide transformer.