Patent ID: 8787712

Claim:
An integrated circuit physical optical Input/Output (I/O) interface for coupling at least one mode of an optical signal between a waveguide external to the integrated circuit and a high refractive index waveguide internal to the integrated circuit, the physical optical interface comprising: a first I/O waveguide adapted to convey an external optical signal near the integrated circuit along an external signal path and having a first effective refractive index, said first I/O wavequide having a first core, said first core having a first bulk refractive index; and a second waveguide forming part of the integrated circuit and adapted to convey an internal optical signal along an internal signal path, said second waveguide having a second effective refractive index and having a second core having a second bulk refractive index higher than said first bulk refractive index, wherein said second core having a reduced thickness over at least a portion to exhibit a constant effective refractive index that matches said first effective refractive index of said first I/O waveguide over said at least a portion, said second core and said first core being arranged with an overlap there between and a separation distance there between over said at least a portion of said second core to permit tunnel coupling of said at least one mode of said optical signal between said internal signal path and said external signal path.