# US 12,119,607 B2 · Tunable laser > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,119,607 B2 - Document ID: US12119607B2 - Status: Granted - Kind: B2 - Application number: 17/418,597 - Filed: 2019-12-26 - Published: 2022-03-10 - Granted: 2024-10-15 - Earliest claimed: 2019-01-07 - Assignees: Nippon Telegraph and Telephone Corporation - Applicants: Nippon Telegraph and Telephone Corporation - Inventors: Yusuke Muranaka; Shinji Matsuo; Nobuhiro Nunoya; Toshikazu Hashimoto - Web page: https://patentgrep.com/patent/US12119607B2 ## CPC - H01S 3/137: for stabilising of frequency - H01S 5/142: {which comprises an additional resonator} - H01S 3/063: Waveguide lasers, {i.e. whereby the dimensions of the waveguide are of the order of the light wavelength (waveguide gas lasers H01S3/0315)} - H01S 3/083: Ring lasers {(fibre ring lasers H01S3/06791)} - H01S 5/22: having a ridge or stripe structure - G02B 6/12007: {forming wavelength selective elements, e.g. multiplexer, demultiplexer} - H01S 3/106: by controlling devices placed within the cavity ({H01S3/10076,} H01S3/13 take precedence) - H01S 5/026: Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers (stabilisation of output H01S5/06) - H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A wavelength tunable laser includes a filter region having a wavelength selection function on light from a gain region, wherein the filter region is a Sagnac interferometer and includes two ring resonators. The ring resonator has two optical couplers, and first and second curved waveguides connecting the two optical couplers, each of the two optical couplers is configured to receive input of the light from the gain region through an input-output port, to couple light of a resonant peak to a bar port of the input-output port, and to couple light except light at a resonant peak wavelength to a cross port of the input-output port, and the first curved waveguide connects the bar ports of the input-output ports of the two optical couplers, and the second curved waveguide connects the cross ports of ports, of two optical couplers, that the first curved waveguide is connected to. ## Claims ### Claim 1 A wavelength tunable laser comprising a filter region having a wavelength selection function on light from a gain region, wherein the filter region is a Sagnac interferometer that functions as a loop mirror, and includes two ring resonators, the ring resonator has two optical couplers, and first and second curved waveguides connecting the two optical couplers, each of the two optical couplers is configured to receive input of the light from the gain region through an input-output port, to split the light into light of a resonant peak and light except light at a resonant peak wavelength, to couple the light of the resonant peak to a bar port of the input-output port, and to couple the light except the light at the resonant peak wavelength to a cross port of the input-output port, the first curved waveguide connects the bar ports of the input-output ports of the two optical couplers, and the second curved waveguide connects the cross ports of ports, of the two optical couplers, that the first curved waveguide is connected to; inside a loop of the ring resonator, two radiation waveguides are connected to the cross ports of the input-output ports of the two optical couplers and discard the light except the light at the resonant peak wavelength, and, the radiation waveguide are connected to an elliptical slab waveguide inside the loop of the ring resonator. ### Claim 2 (depends on 1) The wavelength tunable laser according to claim 1, wherein each of the two optical couplers is configured such that a ratio of the light, except the light at the resonant peak wavelength, that is coupled to the radiation waveguide is higher than a ratio of the light, of the resonant peak, that is coupled to the first curved waveguide. ### Claim 3 (depends on 2) The wavelength tunable laser according to claim 2, wherein the radiation waveguides are connected, inside the loop of the ring resonator, to a waveguide having an active layer identical to an active layer of the gain region for the laser. ### Claim 4 (depends on 2) The wavelength tunable laser according to claim 2, wherein the optical coupler is a multimode interference coupler. ### Claim 5 (depends on 2) The wavelength tunable laser according to claim 2, wherein the optical coupler is a directional coupler. ### Claim 6 (depends on 4) The wavelength tunable laser according to claim 4, wherein the radiation waveguides are connected to the elliptical slab waveguide at an acute angle. ### Claim 7 (depends on 6) The wavelength tunable laser according to claim 6, wherein the optical coupler is a multimode interference coupler. ### Claim 8 (depends on 6) The wavelength tunable laser according to claim 6, wherein the optical coupler is a directional coupler. ### Claim 9 (depends on 1) The wavelength tunable laser according to claim 1, wherein the optical coupler is a multimode interference coupler. ### Claim 10 (depends on 1) The wavelength tunable laser according to claim 1, wherein the optical coupler is a directional coupler. ### Claim 11 A wavelength tunable laser comprising filter region having wavelength selection function on light from a gain region, wherein the filter region is a Sagnac interferometer that functions as a loop mirror, and includes two ring resonators, the ring resonator has two optical couplers, and first and second curved waveguides connecting the two optical couplers, each of the two optical couplers is configured to receive input of the light from the gain region through an input-output port, to split the light into light of a resonant peak and light except light at a resonant peak wavelength, to couple the light of the resonant peak to a bar port of the input-output port, and to couple the light except the light at the resonant peak wavelength to a cross port of the input-output port, the first curved waveguide connects or ports of the input-output ports of the two optical couplers, and the second cu connects the cross ports of ports, of the two optical couplers, that the first curve e is connected to, inside a loop of the ng resonator, two radiation waveguides are connected to the cross ports of put-output ports of two optical couplers and discard the light except the light at the resonant peak wavelengths, and the radiation waveguides are connected, inside the loop of the ring resonator, to a waveguide having an active layer identical to an active layer of the gain region for the laser. ### Claim 12 (depends on 11) The wavelength tunable laser according to claim 11, wherein the optical coupler is a multimode interference coupler. ### Claim 13 (depends on 11) The wavelength tunable laser according to claim 11, wherein the optical coupler is a directional coupler.