# US 11,112,561 B2 · Variable wavelength filter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,112,561 B2 - Document ID: US11112561B2 - Status: Granted - Kind: B2 - Application number: 16/970,270 - Filed: 2019-03-04 - Published: 2021-05-13 - Granted: 2021-09-07 - Earliest claimed: 2018-03-07 - Assignees: Nippon Telegraph and Telephone Corporation - Applicants: Nippon Telegraph and Telephone Corporation - Inventors: Kenya Suzuki; Takashi Go; Osamu Moriwaki; Ai Yanagihara; Keita Yamaguchi - Web page: https://patentgrep.com/patent/US11112561B2 ## CPC - G02B 6/12014: {characterised by the wavefront splitting or combining section, e.g. grooves or optical elements in a slab waveguide} - G02B 6/12026: {characterised by means for reducing the temperature dependence} - G02B 6/12009: {comprising arrayed waveguide grating [AWG] devices, i.e. with a phased array of waveguides} - G02B 6/13: Integrated optical circuits characterised by the manufacturing method - G02B 6/29325: {of the slab or planar or plate like form, i.e. confinement in a single transverse dimension only (integrated circuit planar waveguide arrangements G02B6/12007; specially adapted for lighting G02B6/0011)} - G02F 1/01: for the control of the intensity, phase, polarisation or colour (G02F1/29, G02F1/35 take precedence) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS ## Abstract Provided is a variable wavelength filter having a wide variable wavelength range. In the variable wavelength filter, a slab waveguide that is a component of an arrayed-waveguide grating has a groove into which a resin is inserted. The groove intersects with a plurality of line segments A joining a place of connection between an input light waveguide and the slab waveguide to places of connection between respective array waveguides and the slab waveguide. The groove is formed such that a total length LA of an intersection of the groove and each of the line segments A monotonously increases or decreases between the adjacent line segments A with a difference in the total length LA between the adjacent line segments A being constant. ## Claims ### Claim 1 A variable wavelength filter comprising: on a substrate, an input light waveguide; an arrayed-waveguide grating including a first slab waveguide, two or more array waveguides, and a second slab waveguide; and at least one output light waveguide, wherein at least one of the first slab waveguide and the second slab waveguide includes a groove and a resin inserted into the groove, wherein the groove is formed: such that, on condition that the groove intersects with a plurality of line segments A joining a place of connection between the input light waveguide and the first slab waveguide to places of connection between the respective array waveguides and the first slab waveguide, a total length LA of an intersection of the groove and each of the line segments A monotonously increases or decreases between the adjacent line segments A with a difference in the total length LA between the adjacent line segments A being constant, or such that, on condition that the groove intersects with a plurality of line segments B joining a place of connection between the at least one output light waveguide and the second slab waveguide to places of connection between the respective array waveguides and the second slab waveguide, a total length LB of an intersection of the groove and each of the line segments B monotonously increases or decreases between the adjacent line segments B with a difference in the total length LB between the adjacent line segments B being constant, and wherein the variable wavelength filter includes temperature control means to heat or cool or heat and cool the substrate and temperature detection means to detect a temperature of the substrate. ### Claim 2 (depends on 1) The variable wavelength filter according to claim 1, wherein the first slab waveguide and the second slab waveguide each include the groove and the resin inserted into the groove, wherein the groove in each of the first and the second slab waveguides is formed such that the total length LA monotonously increases between the adjacent line segments A with a difference in the total length LA between the adjacent line segments A being constant and that the total length LB monotonously increases between the adjacent line segments B with a difference in the total length LB between the adjacent line segments B being constant or such that the total length LA monotonously decreases between the adjacent line segments A with a difference in the total length LA between the adjacent line segments A being constant and that the total length LB monotonously decreases between the adjacent line segments B with a difference in the total length LB between the adjacent line segments B being constant, and wherein both the resin in the first slab waveguide and the resin in the second slab waveguide are heated or cooled by the temperature control means. ### Claim 3 (depends on 2) The variable wavelength filter according to either claim 2, further comprising: a 1×N optical switch, where N is an integer greater than or equal to 2, the 1×N optical switch being disposed between the input light waveguide and the arrayed-waveguide grating; and an M×1 optical switch, where M is an integer greater than or equal to 2, the M×1 optical switch being disposed between the arrayed-waveguide grating and the at least one output light waveguide. ### Claim 4 (depends on 3) The variable wavelength filter according to claim 3, further comprising at least one photodiode covering a variable wavelength range of the variable wavelength filter and receiving light emitted from a plurality of outputs of the arrayed-waveguide grating. ### Claim 5 (depends on 2) The variable wavelength filter according to claim 2, further comprising at least one photodiode covering a variable wavelength range of the variable wavelength filter and receiving light emitted from a plurality of outputs of the arrayed-waveguide grating. ### Claim 6 (depends on 1) The variable wavelength filter according to claim 1, wherein the first slab waveguide and the second slab waveguide each include the groove and the resin inserted into the groove, wherein the groove in each of the first and the second slab waveguides is formed such that the total length LA monotonously increases between the adjacent line segments A with a difference in the total length LA between the adjacent line segments A being constant and that the total length LB monotonously decreases between the adjacent line segments B with a difference in the total length LB between the adjacent line segments B being constant or such that the total length LA monotonously decreases between the adjacent line segments A with a difference in the total length LA between the adjacent line segments A being constant and that the total length LB monotonously increases between the adjacent line segments B with a difference in the total length LB between the adjacent line segments B being constant, and wherein the temperature control means is designed to cool the resin in the first slab waveguide and heat the resin in the second slab waveguide or to heat the resin in the first slab waveguide and cool the resin in the second slab waveguide. ### Claim 7 (depends on 6) The variable wavelength filter according to either claim 6, further comprising: a 1×N optical switch, where N is an integer greater than or equal to 2, the 1×N optical switch being disposed between the input light waveguide and the arrayed-waveguide grating; and an M×1 optical switch, where M is an integer greater than or equal to 2, the M×1 optical switch being disposed between the arrayed-waveguide grating and the at least one output light waveguide. ### Claim 8 (depends on 6) The variable wavelength filter according to claim 6, further comprising at least one photodiode covering a variable wavelength range of the variable wavelength filter and receiving light emitted from a plurality of outputs of the arrayed-waveguide grating. ### Claim 9 (depends on 1) The variable wavelength filter according to claim 1, wherein the temperature control means comprises: one of a heating mechanism and a heating-cooling mechanism to individually heat the resin inserted in the groove or to individually heat or cool the inserted resin; and a heat radiation mechanism to let heat radiated from a part of the variable wavelength filter other than the groove in which the heated or cooled resin is inserted. ### Claim 10 (depends on 9) The variable wavelength filter according to claim 9, wherein one of the heating mechanism and the heating-cooling mechanism is disposed in a zone directly below each of the grooves in which the resin is inserted, and wherein the heat radiation mechanism is disposed in a zone on the substrate so as to thermally isolate the heated or cooled resin. ### Claim 11 (depends on 1) The variable wavelength filter according to claim 1, further comprising temperature measurement means designed to individually measure a temperature of the resin inserted in the groove.