# US 12,224,554 B2 · Laser having tapered region > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,224,554 B2 - Document ID: US12224554B2 - Status: Granted - Kind: B2 - Application number: 18/486,968 - Filed: 2023-10-13 - Published: 2024-02-01 - Granted: 2025-02-11 - Earliest claimed: 2020-01-31 - Assignees: Freedom Photonics LLC - Applicants: Freedom Photonics LLC - Inventors: Gordon Barbour Morrison - Web page: https://patentgrep.com/patent/US12224554B2 ## CPC - H01S 5/1007: {Branched waveguides} - H01S 5/04256: {characterised by the configuration} - H01S 5/06256: {with DBR-structure} - H01S 5/101: {Curved waveguide (H01S5/1243 takes precedence)} - H01S 5/1014: {Tapered waveguide, e.g. spotsize converter (H01S5/1064 takes precedence)} - H01S 5/1064: {varying width along the optical axis} - H01S 5/125: Distributed Bragg reflector [DBR] lasers - H01S 5/0612: {controlled by temperature} - H01S 2301/166: Single transverse or lateral mode - H01S 2301/18: Semiconductor lasers with special structural design for influencing the near- or far-field - 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 ## Abstract Various designs of semiconductor lasers may comprise a waveguide having a front region that is configured to support a plurality of transverse laser cavity modes and a rear region that support only one transverse laser cavity mode. These front and rear regions may be disposed between front and rear reflectors and may provide optical gain. Some such designs may be useful for providing higher power single mode semiconductor lasers. ## Claims ### Claim 1 A semiconductor laser comprising: a waveguide comprising: a first waveguide region extending in a longitudinal direction between first and second ends of said first waveguide region and having a width extending in a lateral direction, said width of said first waveguide region being configured such that said first waveguide region supports a single bound transverse mode; a second waveguide region extending in the longitudinal direction between said first and second ends of said second waveguide region and having a width extending in the lateral direction; and first and second optical reflectors, said first and second waveguide regions disposed between said first and second optical reflectors, said first optical reflector closer to said first end of said first waveguide region than said second end of said first waveguide region, said second optical reflector closer to said second end of said second waveguide region than said first end of said second waveguide region, said first and second optical reflectors disposed with respect to each other to form a laser cavity therebetween, wherein the width of said second waveguide region at said second end of said second waveguide region is larger than the width at said first end of said second waveguide region; wherein a reflectivity of the first optical reflector is greater than 20%; wherein the second waveguide region is configured to provide optical gain for light propagating within said laser cavity; wherein the first waveguide region does not provide the optical gain for the light propagating within said laser cavity; and wherein said second waveguide region is configured to support and provide optical gain to a plurality of bound transverse modes, and the laser cavity sustains and outputs a single transverse mode. ### Claim 2 (depends on 1) The semiconductor laser of claim 1, wherein the second waveguide region is flared. ### Claim 3 (depends on 1) The semiconductor laser of claim 1, wherein the first waveguide region is flared. ### Claim 4 (depends on 1) The semiconductor laser of claim 1, wherein the width of the second waveguide region increases progressively from said first end to said second end. ### Claim 5 (depends on 1) The semiconductor laser of claim 1, wherein said first and second waveguide regions each have an average width, and said average width of said first waveguide region is smaller than the average width of said second waveguide region. ### Claim 6 (depends on 1) The semiconductor laser of claim 1, wherein the width of said first waveguide region is the same at said first and second ends. ### Claim 7 (depends on 1) The semiconductor laser of claim 1, wherein the width of said second waveguide region along most of the longitudinal direction is greater than a maximum width of said first waveguide region. ### Claim 8 (depends on 1) The semiconductor laser of claim 1, wherein the width of said second waveguide region along an entire longitudinal direction is equal to or greater than a maximum width of said first waveguide region. ### Claim 9 (depends on 1) The semiconductor laser of claim 1, wherein the width of said first waveguide region is in a range from 1 to 20 microns. ### Claim 10 (depends on 1) The semiconductor laser of claim 1, wherein the width of said second waveguide region is in a range from 10 to 500 microns. ### Claim 11 (depends on 1) The semiconductor laser of claim 1, wherein said first optical reflector comprises a sampled grating distributed Bragg reflector, a comb mirror, or a narrow band reflector. ### Claim 12 (depends on 1) The semiconductor laser of claim 1, wherein said second optical reflector comprises a sampled grating distributed Bragg reflector, a comb mirror, or a narrow band reflector. ### Claim 13 (depends on 1) The semiconductor laser of claim 1, wherein said second optical reflector comprises a broad band mirror. ### Claim 14 (depends on 1) The semiconductor laser of claim 1, wherein said second optical reflector comprises a partially reflecting facet. ### Claim 15 (depends on 1) The semiconductor laser of claim 1, wherein said first optical reflector is configured to provide the optical gain. ### Claim 16 (depends on 1) The semiconductor laser of claim 1, further comprising a phase section configured to introduce a change in optical path of an optical signal in the laser cavity, wherein the phase section is configured to be electrically or thermally controlled. ### Claim 17 (depends on 1) The semiconductor laser of claim 1, further comprising an optical amplifier at said second end of said second waveguide region. ### Claim 18 (depends on 1) The semiconductor laser of claim 1, wherein the laser comprises a Y branch laser. ### Claim 19 (depends on 1) The semiconductor laser of claim 1, wherein the first and second waveguide regions are included in one branch of a Y branch laser. ### Claim 20 (depends on 1) The semiconductor laser of claim 1, wherein said first waveguide region comprises a curved optical path.