# US 12,111,493 B2 · Optical connection structure and method for manufacturing the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,111,493 B2 - Document ID: US12111493B2 - Status: Granted - Kind: B2 - Application number: 17/630,042 - Filed: 2019-08-16 - Published: 2022-09-01 - Granted: 2024-10-08 - Earliest claimed: 2019-08-16 - Assignees: Nippon Telegraph and Telephone Corporation - Applicants: Nippon Telegraph and Telephone Corporation - Inventors: Yohei Saito; Kota Shikama; Atsushi Aratake - Web page: https://patentgrep.com/patent/US12111493B2 ## CPC - G02B 6/1221: {made from organic materials} - G02B 6/262: {Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements} - G02B 6/4212: {the intermediate optical element being a coupling medium interposed therebetween, e.g. epoxy resin, refractive index matching material, index grease, matching liquid or gel} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A first optical waveguide, a second optical waveguide, a connection optical waveguide including a resin core that optically connects the first optical waveguide and the second optical waveguide are included. The resin core is covered with cladding. The second optical waveguide has a core with a diameter that is different from a diameter of a core of the first optical waveguide. The resin core is disposed between an end surface of the first optical waveguide and an end surface of the second optical waveguide and optically connects the first optical waveguide and the second optical waveguide. Moreover, the resin core is configured with a cured photo-curable resin. ## Claims ### Claim 1 An optical connection structure comprising: a first optical waveguide; a second optical waveguide having an end surface disposed to face an end surface of the first optical waveguide, and the second optical waveguide having a core diameter different from a core diameter of the first optical waveguide; a holding member configured to secure the first optical waveguide and the second optical waveguide, wherein the holding member comprises an insertion portion into which the first optical waveguide and the second optical waveguide are to be inserted; a spacer comprising a film disposed at a center of the insertion portion between the end surface of the first optical waveguide and the end surface of the second optical waveguide to define an interval between the end surface of the first optical waveguide and the end surface of the second optical waveguide, wherein a bottom surface of the spacer is higher than a bottom surface of the first optical waveguide and a bottom surface of the second optical waveguide in a cross-sectional view; and a connection optical waveguide disposed between the end surface of the first optical waveguide and the end surface of the second optical waveguide to optically connect the first optical waveguide to the second optical waveguide, the connection optical waveguide including a resin core comprising a photo-curable resin, wherein a core diameter of the resin core gradually changes from a state adapted to the core diameter of the first optical waveguide to a state adapted to the core diameter of the second optical waveguide from a side facing the first optical waveguide to a side facing the second optical waveguide. ### Claim 2 (depends on 1) The optical connection structure according to claim 1, wherein: a first end surface of the resin core facing the first optical waveguide and a first end surface of a core of the first optical waveguide abut each other; and a second end surface of the resin core facing the second optical waveguide and a second end surface of a core of the second optical waveguide abut each other. ### Claim 3 (depends on 2) The optical connection structure according to claim 2, wherein: the core diameter of a side of the resin core facing the first optical waveguide is substantially identical with a core system of the first optical waveguide; and the core diameter of a side of the resin core facing the second optical waveguide is substantially identical with a core system of the second optical waveguide. ### Claim 4 (depends on 1) The optical connection structure according to claim 1, wherein a hole diameter of the insertion portion gradually decreases from each outer end of the insertion portion toward the spacer. ### Claim 5 (depends on 1) The optical connection structure according to claim 1, wherein the spacer is in a shape of a U or an arc. ### Claim 6 A method of manufacturing an optical connection structure, the optical connection structure comprising a first optical waveguide, a second optical waveguide having a core diameter different from a core diameter of the first optical waveguide, and a connection optical waveguide disposed between an end surface of the first optical waveguide and an end surface of the second optical waveguide to optically connect the first optical waveguide to the second optical waveguide, the connection optical waveguide including a resin core comprising a photo-curable resin, wherein a core diameter of the resin core gradually changes from a state adapted to the core diameter of the first optical waveguide to a state adapted to the core diameter of the second optical waveguide from a side facing the first optical waveguide to a side facing the second optical waveguide, the method comprising: disposing the first optical waveguide and the second optical waveguide such that the end surface of the first optical waveguide and the end surface of the second optical waveguide face each other and are separated by a predetermined interval, wherein the first optical waveguide and the second optical waveguide are secured by a holding member comprising an insertion portion into which the first optical waveguide and the second optical waveguide are inserted, and wherein a spacer comprising a film and disposed at a center of the insertion portion between the end surface of the first optical waveguide and the end surface of the second optical waveguide defines the predetermined interval between the end surface of the first optical waveguide and the end surface of the second optical waveguide; after providing the spacer, disposing the photo-curable resin between the end surface of the first optical waveguide and the end surface of the second optical waveguide; and forming the resin core by guiding a curing light that performs photo-curing of the photo-curable resin through each of the first optical waveguide and the second optical waveguide to perform, with the curing light, the photo-curing of the photo-curable resin disposed between the end surface of the first optical waveguide and the end surface of the second optical waveguide. ### Claim 7 (depends on 6) The method according to claim 6, further comprising: after forming the resin core, removing the photo-curable resin that is uncured; and after removing the photo-curable resin that is uncured, forming cladding where the resin core is to be embedded, between the end surface of the first optical waveguide and the end surface of the second optical waveguide. ### Claim 8 (depends on 6) The method according to claim 6, wherein forming the resin core comprises guiding a signal light with a wavelength that is not absorbed by the photo-curable resin that is uncured between the first optical waveguide and the second optical waveguide in addition to the curing light to perform the photo-curing of the photo-curable resin into a state where transmission intensity of the signal light is at a maximum level. ### Claim 9 (depends on 6) The method according to claim 6, wherein a hole diameter of the insertion portion gradually decreases from each outer end of the insertion portion toward the spacer. ### Claim 10 (depends on 6) The method according to claim 6, wherein the spacer is in a shape of a U or an arc. ### Claim 11 A method of providing an optical connection structure, the method comprising: providing a first optical waveguide and a second optical waveguide, wherein an end surface of the first optical waveguide is disposed to face an end surface of the second optical waveguide, and wherein the second optical waveguide has a core diameter different from a core diameter of the first optical waveguide; providing a holding member for securing the first optical waveguide and the second optical waveguide, wherein the holding member comprises an insertion portion into which the first optical waveguide and the second optical waveguide are inserted; providing a spacer comprising a film disposed at a center of the insertion portion between the end surface of the first optical waveguide and the end surface of the second optical waveguide to define an interval between the end surface of the first optical waveguide and the end surface of the second optical waveguide; and after providing the spacer, disposing a connection optical waveguide between the end surface of the first optical waveguide and the end surface of the second optical waveguide to optically connect the first optical waveguide to the second optical waveguide, the connection optical waveguide including a resin core comprising a photo-curable resin, wherein a core diameter of the resin core gradually changes from a state adapted to the core diameter of the first optical waveguide to a state adapted to the core diameter of the second optical waveguide from a side facing the first optical waveguide to a side facing the second optical waveguide. ### Claim 12 (depends on 11) The method according to claim 11, wherein: a first end surface of the resin core facing the first optical waveguide and a first end surface of a core of the first optical waveguide abut each other; and a second end surface of the resin core facing the second optical waveguide and a second end surface of a core of the second optical waveguide abut each other. ### Claim 13 (depends on 12) The method according to claim 12, wherein: the core diameter of a side of the resin core facing the first optical waveguide is substantially identical with a core system of the first optical waveguide; and the core diameter of a side of the resin core facing the second optical waveguide is substantially identical with a core system of the second optical waveguide. ### Claim 14 (depends on 11) The method according to claim 11, wherein a hole diameter of the insertion portion gradually decreases from each outer end of the insertion portion toward the spacer. ### Claim 15 (depends on 11) The method according to claim 11, wherein the spacer is in a shape of a U or an arc.