# US 2014/0153084 A1 · Device and passive method for the coherent combination of two amplified and/or spectrally broadened optical beams > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0153084 A1 - Document ID: US20140153084A1 - Status: Published application - Kind: A1 - Application number: 14/232,314 - Filed: 2012-07-11 - Published: 2014-06-05 - Earliest claimed: 2011-07-11 - Assignees: Amplitude Systemes; Ecole Polytechnique - Inventors: Dimitris Papadopoulos; Marc Hanna; Louis Daniault; Yoann Zaouter; Frederic Druon - Web page: https://patentgrep.com/patent/US20140153084A1 ## CPC - H01S 3/2308: {Amplifier arrangements, e.g. MOPA} - H01S 3/005: {Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping (shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B)} - H01S 3/0057: {Temporal shaping, e.g. pulse compression, frequency chirping (soliton generation and propagation G02F1/3513, H01S3/063 and H01S3/108)} - H01S 3/06754: {Fibre amplifiers (H01S3/06708 takes precedence)} - H01S 3/2333: {Double-pass amplifiers} - H01S 3/0064: {Anti-reflection devices, e.g. optical isolaters (absorbing layers for marking or protecting purposes in laser working B23K26/50; magneto-optical non-reciprocal devices G02F1/093, G02F1/0955)} - H01S 3/06758: {Tandem amplifiers} - H01S 3/06787: {Bidirectional amplifier} - H01S 3/10076: {using optical phase conjugation, e.g. phase conjugate reflection} - H01S 2301/04: Gain spectral shaping, flattening - 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 A method and passive device for the coherent combination of two amplified and/or spectrally broadened optical beams using at least one bidirectional optical component (A1, A2), the device includes an amplitude division ring interferometer having optical splitting and recombining elements disposed so as to receive an incident optical beam (S0) and to split it spatially into a first secondary input beam (H1) and a second secondary input beam (H2), optical guiding elements disposed so as to define an optical path in the form of a ring in the interferometer, the at least one bidirectional optical component being disposed on the optical path of the ring interferometer, the splitting and recombining elements being disposed in such a way as to receive and to recombine spatially, temporally and coherently the first secondary output beam (H1″) and the second secondary output beam (H2″), so as to form a coherent output beam. ## Claims ### Claim 1 A passive device for the coherent combination of two amplified and/or spectrally broadened optical beams, characterized in that said device comprises: an amplitude-division ring interferometer, said interferometer comprising: optical splitting and recombining means (3, 31, 32, 33) arranged so as to receive an incident optical beam (S0) and to spatially split it into a first secondary input beam (H1) and a second secondary input beam (H2); optical guiding means (M1, M2, M3, M4, M11, M12, M13) arranged so as to define a ring optical path in said interferometer, said first secondary input beam (H1) travelling through the ring interferometer in a clockwise direction to form a first secondary output beam (H1″) and respectively said second secondary input beam (H2) travelling through the ring interferometer in a counterclockwise direction to form a second secondary output beam (H2″); at least one bidirectional optical component (A1, A2) arranged on the optical path of said ring interferometer, said at least one bidirectional optical component (A1, A2) being adapted to amplify and/or spectrally broaden on the one hand a secondary optical beam (H1, H2) propagating in a clockwise direction and on the other hand a secondary optical beam (H1, H2) propagating in a counterclockwise direction; said splitting and recombining means (3, 31, 32, 33) being arranged so as to receive and to spatially, temporally and coherently recombine said first secondary output beam (H1″) and said second secondary output beam (H2″), to form an amplified and/or spectrally broadened output coherent beam (S1, S2, S3). ### Claim 2 (depends on 1) The passive device for coherent combination according to claim 1, further comprising optical isolation means (2, 21, 22, 23) arranged upstream of said ring interferometer so as to spatially split the incident optical beam (S0) and the amplified and/or spectrally broadened output coherent beam (S1, S2, S3). ### Claim 3 (depends on 1) The passive device for coherent combination according to claim 1, wherein said optical guiding means (M1, M2, M3, M4, M11, M12, M13) comprise highly reflective mirrors (M1, M2, M3, M4), chirped mirrors (M11, M12, M13), optical fiber sections, and/or polarization maintaining optical fiber sections and/or specific dispersing optical fiber sections. ### Claim 4 (depends on 1) The passive device for coherent combination according to claim 1, further comprising a reflective mirror (M4) or a Faraday mirror (44) arranged on an output of the splitting and recombining optical means so as to reflect the first secondary output beam (H1″) and the second secondary output beam (H2″) toward the ring interferometer, so that said first secondary beam and second secondary beam travel a second time through the ring interferometer before being coherently recombined. ### Claim 5 (depends on 1) The passive device for coherent combination according to claim 1, wherein said splitting and recombining optical means comprise a polarization splitter (31, 32, 33) arranged so as to split the incident beam (S0) into a first secondary input beam (H1) and a second secondary input beam (H2), said first and second secondary input beams (H1, H2) being linearly polarized in orthogonal polarizations, said device further comprising polarization means (4, 41, 42, 43, 44, 45, 46, 47) arranged on the path of the ring interferometer, said polarization means (4, 41, 42, 43, 44, 45, 46, 47) being configured so that the first secondary output beam (H1″) is linearly polarized with a same polarization as the second secondary input beam (H2) and so that the second secondary output beam (H2″) is linearly polarized with a same polarization as the first secondary input beam (H1). ### Claim 6 (depends on 5) The passive device for coherent combination according to claim 5, wherein said polarization means comprise a half-wave plate (4, 47), or two quarter-wave plates (45, 46) or two half-wave plates, or a Faraday rotator (42) or a Faraday mirror (44), or a sub-unit comprising a polarization splitting cube (41), a quarter-wave plate (42) and a reflective mirror (43). ### Claim 7 (depends on 5) The passive device for coherent combination according to claim 5, wherein said optical splitting and recombining means comprise a polarizer and/or a wave plate (22, 24, 27) and/or an optical isolator (23), configured so as to recombine in a same polarization state said first secondary output beam (H″1) and said second secondary output beam (H″2) orthogonally polarized relative to each other. ### Claim 8 (depends on 1) The passive device for coherent combination according to claim 1, wherein said at least one bidirectional optical component (A1, A2) comprises an optical amplifier (A1). ### Claim 9 (depends on 1) The passive device for coherent combination according to claim 1, wherein said at least one bidirectional optical component (A1, A2) comprises a first bidirectional optical amplifier (A1) and a second bidirectional optical amplifier (A2), said optical amplifiers (A1, A2) being arranged in series on the optical path of the ring interferometer. ### Claim 10 (depends on 9) The passive device for coherent combination according to claim 9, wherein the first optical amplifier (A1) comprises a first optical fiber amplifier and said second optimal amplifier (A2) comprises a second optical fiber amplifier. ### Claim 11 (depends on 1) The passive device for coherent combination according to claim 1, wherein said at least one bidirectional optical component (A1, A2) comprises a first bidirectional optical component (A1) adapted to spectrally broaden said secondary optical beams (H1, H′2) and a second bidirectional optical component (A2) adapted to spectrally broaden said secondary optical beams (H2, H′1). ### Claim 12 A method for the passive coherent combination of two amplified and/or spectrally broadened optical beams, said method comprising the following steps: coupling an incident optical beam (S0) to an amplitude-division ring interferometer, said interferometer comprising optical splitting and recombining means (3, 31, 32, 33) and at least one bidirectional optical component (A1, A2) arranged on the optical path of said ring interferometer, said at least one optical component (A1, A2) being adapted to amplify and/or spectrally broaden on the one hand a secondary optical beam propagating in a clockwise direction in the interferometer and on the other hand a secondary optical beam propagating in a counterclockwise direction in the interferometer; spatially amplitude-splitting the incident optical beam (S0) by said optical splitting and recombining means (3, 31, 32, 33) into a first secondary input beam (H1) and a second secondary input beam (H2); optically guiding said first secondary input beam (H1) so that it travels through the ring interferometer in a clockwise direction and so that said first secondary input beam (H1) is amplified and/or spectrally broadened by said at least one optical component (A1, A2) to form a first secondary output beam (H″1) directed toward said optical splitting and recombining means (3, 31, 32, 33); optically guiding said second secondary input beam (H2) so that it travels through the ring interferometer in a counterclockwise direction and so that said second secondary input beam (H2) is amplified and/or spectrally broadened by said at least one optical component (A1, A2) to form a second secondary output beam (H″2) directed toward said optical splitting and recombining means (3, 31, 32, 33); coherently spatially recombining the first secondary output beam (H″1) and the second secondary output beam (H″2) by said optical splitting and recombining means (3, 31, 32, 33) to form an amplified and/or spectrally broadened output coherent beam (H1, S2, S3). ### Claim 13 (depends on 12) The method for coherent combination according to claim 12, wherein: the spatial amplitude splitting of the incident optical beam (S0) into a first secondary input beam (H1) and a second secondary input beam (H2) comprises a polarization splitting, said first secondary input beam (H1) and second secondary input beam (H2) being polarized orthogonally, the optical guiding in the ring interferometer comprises a polarization rotation of 90 degrees, said first secondary output beam (H″1) having the same polarization as the second secondary input beam (H2) and the second secondary output beam (H″2) having the same polarization as the first secondary input beam (H1), the coherent spatial recombination comprises a recombination of the first secondary output beam (H″1) and of the second secondary output beam (H″2), the polarizations of the first secondary output beam (H″1) and of the second secondary output beam (H″2) being orthogonal. ### Claim 14 (depends on 2) The passive device for coherent combination according to claim 2, wherein said optical guiding means (M1, M2, M3, M4, M11, M12, M13) comprise highly reflective mirrors (M1, M2, M3, M4), chirped mirrors (M11, M12, M13), optical fiber sections, and/or polarization maintaining optical fiber sections and/or specific dispersing optical fiber sections. ### Claim 15 (depends on 2) The passive device for coherent combination according to claim 2, further comprising a reflective mirror (M4) or a Faraday mirror (44) arranged on an output of the splitting and recombining optical means so as to reflect the first secondary output beam (H1″) and the second secondary output beam (H2″) toward the ring interferometer, so that said first secondary beam and second secondary beam travel a second time through the ring interferometer before being coherently recombined. ### Claim 16 (depends on 3) The passive device for coherent combination according to claim 3, further comprising a reflective mirror (M4) or a Faraday mirror (44) arranged on an output of the splitting and recombining optical means so as to reflect the first secondary output beam (H1″) and the second secondary output beam (H2″) toward the ring interferometer, so that said first secondary beam and second secondary beam travel a second time through the ring interferometer before being coherently recombined. ### Claim 17 (depends on 2) The passive device for coherent combination according to claim 2, wherein said splitting and recombining optical means comprise a polarization splitter (31, 32, 33) arranged so as to split the incident beam (S0) into a first secondary input beam (H1) and a second secondary input beam (H2), said first and second secondary input beams (H1, H2) being linearly polarized in orthogonal polarizations, said device further comprising polarization means (4, 41, 42, 43, 44, 45, 46, 47) arranged on the path of the ring interferometer, said polarization means (4, 41, 42, 43, 44, 45, 46, 47) being configured so that the first secondary output beam (H1″) is linearly polarized with a same polarization as the second secondary input beam (H2) and so that the second secondary output beam (H2″) is linearly polarized with a same polarization as the first secondary input beam (H1). ### Claim 18 (depends on 3) The passive device for coherent combination according to claim 3, wherein said splitting and recombining optical means comprise a polarization splitter (31, 32, 33) arranged so as to split the incident beam (S0) into a first secondary input beam (H1) and a second secondary input beam (H2), said first and second secondary input beams (H1, H2) being linearly polarized in orthogonal polarizations, said device further comprising polarization means (4, 41, 42, 43, 44, 45, 46, 47) arranged on the path of the ring interferometer, said polarization means (4, 41, 42, 43, 44, 45, 46, 47) being configured so that the first secondary output beam (H1″) is linearly polarized with a same polarization as the second secondary input beam (H2) and so that the second secondary output beam (H2″) is linearly polarized with a same polarization as the first secondary input beam (H1). ### Claim 19 (depends on 6) The passive device for coherent combination according to claim 6, wherein said optical splitting and recombining means comprise a polarizer and/or a wave plate (22, 24, 27) and/or an optical isolator (23), configured so as to recombine in a same polarization state said first secondary output beam (H″1) and said second secondary output beam (H″2) orthogonally polarized relative to each other.