Semiconductor waveguide and impedance-matched detector

Claim 1

An impedance-matched optical detector, comprising: a substrate; an optical waveguide layer linearly extending along a surface of said substrate and having a first refractive index for propagating therein light of a predetermined wavelength parallel to said surface; a light absorbing layer for absorbing said light of said predetermined wavelength and thereby providing an electrical signal for said detector, said light absorbing layer being formed adjacent to a first linear portion of said optical waveguide layer and having a second refractive index different from said first refractive index; an impedance matching region formed between said waveguide layer and said light absorbing layer adjacent within an optical intensity distribution to only a second linear portion of said optical waveguide layer and having a third refractive index between said first and second refractive indices, said third refractive index being averaged over said impedance matching region; and cladding media disposed immediately above and below said optical waveguide layer at least in linear portions away from said first and second linear portions, said cladding media having respective refractive indices smaller than said first refractive index and respective thicknesses larger than corresponding optical intensity distributions in said cladding media.