# US 8,787,712 B2 · Low loss directional coupling between highly dissimilar optical waveguides for high refractive index integrated photonic circuits > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,712 B2 - Document ID: US8787712B2 - Status: Granted - Kind: B2 - Application number: 13/977,341 - Filed: 2011-12-29 - Published: 2013-12-05 - Granted: 2014-07-22 - Earliest claimed: 2010-12-29 - Assignees: Socpra Sciences Et Genie S.E.C. - Applicants: Etienne Grondin; Guillaume Beaudin; Vincent Aimez; Richard Ares; Paul G. Charette - Inventors: Etienne Grondin; Guillaume Beaudin; Vincent Aimez; Richard Ares; Paul G. Charette - Web page: https://patentgrep.com/patent/US8787712B2 ## CPC - G02B 6/1223: {high refractive index type, i.e. high-contrast waveguides} - B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals - G02B 6/30: for use between fibre and thin-film device - G02B 6/2821: {using lateral coupling between contiguous fibres to split or combine optical signals} - G02B 6/3652: {the additional structures being prepositioning mounting areas, allowing only movement in one dimension, e.g. grooves, trenches or vias in the microbench surface, i.e. self aligning supporting carriers} - G02B 6/3692: {with surface micromachining involving etching, e.g. wet or dry etching steps (surface micromachining involving subtractive techniques B81C1/00055)} - G02B 2006/12061: {Silicon} - G02B 2006/12147: {Coupler} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES ## Abstract An optocoupler, an optical interconnect and method of manufacture providing same are provided for coupling an optical signal between a high refractive index waveguide of an integrated circuit and a waveguide external to the integrated circuit. The optocoupler includes a thinned high refractive index waveguide having a thickness configured to exhibit an effective refractive index substantially matching a refractive index of the external waveguide. ## Claims ### Claim 1 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. ### Claim 2 (depends on 1) An integrated circuit physical optical I/O interface as claimed in claim 1, said second core comprising a material having a bulk refractive index greater than 2. ### Claim 3 (depends on 1) An integrated circuit physical optical I/O interface as claimed in claim 1, said first core comprising a dielectric material having a bulk refractive index lower than 2. ### Claim 4 (depends on 1) An integrated circuit physical optical I/O interface as claimed in claim 1, said first core comprising an optical fiber having a bulk refractive index lower than 2. ### Claim 5 (depends on 1) An integrated circuit physical optical I/O interface as claimed in claim 1, comprising an optical fiber I/O waveguide having a thin cladding dimensioned to provide said separation distance to provide said tunnel coupling with said second waveguide. ### Claim 6 (depends on 1) An integrated circuit physical optical I/O interface as claimed in claim 1, further comprising a waveguide separation layer dimensioned to provide said separation distance. ### Claim 7 (depends on 1) An integrated circuit physical optical I/O interface as claimed in claim 1, said second core thickness being configured to select one of a TE and a TM incident optical signal polarization. ### Claim 8 (depends on 7) An integrated circuit physical optical I/O interface as claimed in claim 7, said TM incident optical signal polarization being selected while employing a second core thickness exhibiting an effective refractive index matching an effective refractive index of a TM incident optical signal polarization of said first I/O waveguide, said second core thickness being greater than a second core thickness exhibiting an effective refractive index matching a TE incident optical signal polarization of said first I/O waveguide. ### Claim 9 (depends on 7) An integrated circuit physical optical I/O interface as claimed in claim 7, comprising a coupling structure configured for simultaneous TE and TM optical signal polarization coupling. ### Claim 10 (depends on 7) An integrated circuit physical optical I/O interface as claimed in claim 7, said coupling structure being configured to simultaneously couple each of said TE and TM optical signal polarization into corresponding waveguides. ### Claim 11 (depends on 10) An integrated circuit physical optical I/O interface as claimed in claim 10, said coupling structure being further configured to provide said overlap arrangement over a controlled coupling length providing coupling control. ### Claim 12 (depends on 7) An integrated circuit physical optical I/O interface as claimed in claim 7 comprising a signal recombination structure. ### Claim 13 (depends on 7) An integrated circuit physical optical I/O interface as claimed in claim 7, said coupling structure being configured to sequentially couple each of said TE and TM optical signal polarization into a single waveguide. ### Claim 14 (depends on 1) An integrated circuit physical optical I/O interface as claimed in claim 1, said first I/O waveguide comprising an intermediary waveguide and an external optical fiber, said intermediary waveguide having an effective refractive index matching the external optical fiber refractive index. ### Claim 15 (depends on 1) An integrated circuit physical optical I/O interface as claimed in claim 1, said integrated circuit including a layered structure, said layered structure comprising an optical fiber core alignment structure. ### Claim 16 (depends on 15) An integrated circuit physical optical I/O interface as claimed in claim 15, said external optical fiber comprising a circular cross-section cladding, and said alignment structure comprising a V-shaped optical fiber groove. ### Claim 17 An optical signal coupler for coupling at least one mode of an optical signal between at least one first Input/Output (I/O) waveguide and at least one second waveguide forming part of an integrated circuit, each of said at least one first I/O waveguide adapted to convey an external optical signal along an external signal path, said first I/O waveguide having a first effective refractive index and a first core having a first bulk refractive index, each of said at least one second waveguide adapted to convey an internal optical signal along an internal signal path, said at least one second waveguide having a second effective refractive index and a second core having a second bulk refractive index, said second bulk refractive index being higher than said first bulk refractive index, said second core having at least a portion with a reduced thickness to exhibit a constant effective refractive index matching said first effective refractive index of said first I/O waveguide over said at least a portion, said coupler comprising: at least one alignment structure for positioning said first core of at least one first I/O waveguide with respect to said second core of at least one corresponding second waveguide with an overlap therebetween and a separation distance there between over said at least a portion to permit tunnel coupling of said at least one mode of said optical signal between said external signal path and said internal signal path. ### Claim 18 (depends on 17) A coupler as claimed in claim 17, said coupler forming part of integrated circuit packaging of said integrated circuit, said coupler being configured as one of: a complementary structure completing said integrated circuit packaging during assembly; and an integral structure completing said integrated circuit packaging during wafer level manufacture. ### Claim 19 (depends on 18) A coupler as claimed in claim 18, said complementary structure comprising a snap-on device. ### Claim 20 (depends on 19) A coupler as claimed in claim 19, comprising an external optical fiber corresponding to an I/O waveguide, said coupler being configured receive said at least one external optical fiber laterally from at least one side of said integrated circuit.