# US 10,312,663 B2 · Tunable laser device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,312,663 B2 - Document ID: US10312663B2 - Status: Granted - Kind: B2 - Application number: 15/886,901 - Filed: 2018-02-02 - Published: 2018-08-09 - Granted: 2019-06-04 - Earliest claimed: 2017-02-06 - Assignees: Fujitsu Limited - Applicants: Fujitsu Limited - Inventors: Kazumasa Takabayashi; Suguru Akiyama; Tsuyoshi Yamamoto - Web page: https://patentgrep.com/patent/US10312663B2 ## CPC - H01S 5/142: {which comprises an additional resonator} - G01J 1/4257: {applied to monitoring the characteristics of a beam, e.g. laser beam, headlamp beam (monitoring arrangements for lasers in general H01S3/0014)} - G02F 1/011: {in optical waveguides, not otherwise provided for in this subclass} - H01S 5/026: Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers (stabilisation of output H01S5/06) - H01S 5/0687: Stabilising the frequency of the laser - H01S 5/1007: {Branched waveguides} - H01S 5/1025: {Extended cavities} - H01S 5/1032: {Coupling to elements comprising an optical axis that is not aligned with the optical axis of the active region} - H01S 5/1092: {Multi-wavelength lasing} - H01S 5/14: External cavity lasers (H01S5/18 takes precedence; mode locking H01S5/065) - H01S 5/141: {using a wavelength selective device, e.g. a grating or etalon (H01S5/146 takes precedence)} - H01S 5/146: {using a fiber as external cavity} - H01S 5/4068: {with lateral coupling by axially offset or by merging waveguides, e.g. Y-couplers} - G02B 6/2813: {based on multimode interference effect, i.e. self-imaging} - G02B 6/4286: {Optical modules with optical power monitoring} - H01S 5/0262: {Photo-diodes, e.g. transceiver devices, bidirectional devices (H01S5/0265 takes precedence)} - H01S 5/0264: {for monitoring the laser-output} - 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 - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) - 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 - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A apparatus includes a tunable laser configured to include a tunable filter and a mirror; a first optical splitter provided between the tunable filter and the mirror, the first optical splitter including a first port and a second port on a tunable filter side and a third port and a fourth port on a mirror side, in which the tunable filter is coupled to the first port and the mirror is coupled to the third port, respectively; a first optical waveguide coupled to the second port; a second optical waveguide coupled to the fourth port; and an optical coupler with which the first optical waveguide and the second optical waveguide are combined. ## Claims ### Claim 1 A tunable laser device comprising: a tunable laser configured to include a tunable filter and a mirror; a first optical splitter provided between the tunable filter and the mirror, the first optical splitter including a first port and a second port on a tunable filter side and a third port and a fourth port on a mirror side, in which the tunable filter is coupled to the first port and the mirror is coupled to the third port, respectively; a first optical waveguide coupled to the second port; a second optical waveguide coupled to the fourth port; and an optical coupler with which the first optical waveguide and the second optical waveguide are combined. ### Claim 2 (depends on 1) The tunable laser device according to claim 1, wherein, when a first length of the first optical waveguide is L1, a second length of the second optical waveguide is L2, and a distance between the first optical splitter and the mirror is Lc, L1, L2, and Lc are set so that a value of (L1+2Lc)−L2 becomes a delay amount corresponding to light transmission characteristics of a desired cycle. ### Claim 3 (depends on 1) The tunable laser device according to claim 1, wherein the first optical waveguide and the second optical waveguide are set to have a same length. ### Claim 4 (depends on 3) The tunable laser device according to claim 3, wherein the first optical waveguide and the second optical waveguide are symmetrically arranged with respect to the first optical splitter. ### Claim 5 (depends on 1) The tunable laser device according to claim 1, further comprising: a first photodetector configured to detect an output light intensity of the optical coupler; and a second photodetector configured to detect an output light intensity of the tunable laser. ### Claim 6 (depends on 1) The tunable laser device according to claim 1, further comprising: a first photodetector configured to detect an output light intensity of the optical coupler; and a second splitter including a first port on the tunable filter side, a second port and a third port on the mirror side, the first port being coupled to the tunable filter and the second port being coupled to a second photodetector configured to detect an intensity of light branched by the second optical splitter. ### Claim 7 (depends on 6) The tunable laser device according to claim 6, wherein the second optical splitter is coupled between the tunable filter and the first optical splitter. ### Claim 8 (depends on 6) The tunable laser device according to claim 6, wherein the second optical splitter is arranged in the second optical waveguide. ### Claim 9 (depends on 1) The tunable laser device according to claim 1, wherein the tunable filter, the mirror, the first optical splitter, and the optical coupler are formed on a same substrate as an optical waveguide together with the first optical waveguide and the second optical waveguide. ### Claim 10 (depends on 6) The tunable laser device according to claim 6, wherein the tunable filter, the mirror, the first optical splitter, the second optical splitter, and the optical coupler are formed on a substrate as an optical waveguide together with the first optical waveguide and the second optical waveguide. ### Claim 11 (depends on 6) The tunable laser device according to claim 6, wherein the tunable filter, the mirror, the first optical splitter, the second optical splitter, and the first optical coupler are formed on a substrate as an optical waveguide together with the first optical waveguide and the second optical waveguide, and the first photodetector and the second photodetector are integrated on the substrate. ### Claim 12 (depends on 1) The tunable laser device according to claim 1, wherein the optical coupler includes a pair of output ports at which a phase difference of output light is π/2.