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Zhang X, Wang H, Yuan T, Yuan L. Multi-Core Fiber Bragg Grating and Its Sensing Application. SENSORS (BASEL, SWITZERLAND) 2024; 24:4532. [PMID: 39065930 PMCID: PMC11280786 DOI: 10.3390/s24144532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 05/29/2024] [Accepted: 07/11/2024] [Indexed: 07/28/2024]
Abstract
With the increase in the demand for large-capacity optical communication capacity, multi-core optical fiber (MCF) communication technology has developed, and both the types of MCFs and related devices have become increasingly mature. The application of MCFs in the field of sensing has also received more and more attention, among which MCF fiber Bragg grating (FBG) devices have received more and more attention and have been widely used in various fields. In this paper, the main writing methods of MCF FBGs and their sensing applications are reviewed. The future development of the MCF FBG is also prospected.
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Affiliation(s)
- Xiaotong Zhang
- Center for Advanced Manufacturing and Future Industry, Future Technology School, Shenzhen Technology University, Shenzhen 518118, China;
| | - Hongye Wang
- Key Lab of In-Fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, China;
| | - Tingting Yuan
- Center for Advanced Manufacturing and Future Industry, Future Technology School, Shenzhen Technology University, Shenzhen 518118, China;
| | - Libo Yuan
- Photonics Research Center, School of Optoelectronic Engineering, Guilin University of Electronic Technology, Guilin 541004, China
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2
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Balakin AA, Skobelev SA, Litvak AG. Stable few-cycle out-of-phase solitons in a rectangular multi-core fiber. OPTICS LETTERS 2023; 48:6208-6211. [PMID: 38039228 DOI: 10.1364/ol.503453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 10/26/2023] [Indexed: 12/03/2023]
Abstract
Stable out-of-phase soliton-like distributions of the wave field with few-cycle durations are found in fibers consisting of a rectangular lattice of weakly coupled cores. The stability of found distributions for durations larger than the critical value is shown analytically and numerically. Numerical simulation shows that the radiation of linear dispersive waves rather quickly transforms shorter pulses to the found solution with critical duration.
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3
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Li L, Zhu X, Wang J, Zong J, Li M, Meyer J, Chavez-Pirson A, Akbulut M, Norwood RA, Peyghambarian N. Injection-locked highly Yb 3+-doped uncoupled-61-core phosphate fiber laser. OPTICS LETTERS 2023; 48:590-593. [PMID: 36723538 DOI: 10.1364/ol.481018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 12/16/2022] [Indexed: 06/18/2023]
Abstract
Uncoupled multicore fibers are promising platforms for advanced optical communications, optical computing, and novel laser systems. In this paper, an injection-locked highly ytterbium (Yb3+)-doped uncoupled-61-core phosphate fiber laser at 1030 nm is reported. The 61-core fiber with a core-to-core pitch of 20 μm was fabricated with the stack-and-draw technique. Each core doped with 6-wt.% Yb3+ ions has a diameter of 3 μm and numerical aperture of 0.2. Linearly polarized single-frequency output of 9.1 W was obtained from the injection-locked cavity with a 10-cm-long gain fiber at a pump power of 23.6 W. The injection locking of all 61 cores was confirmed by inspecting the longitudinal modes of the individual lasers with a scanning Fabry-Perot interferometer. The performance of the injection-locked 61-core fiber laser was characterized and compared to that of the free-running operation in terms of optical spectrum, near- and far-field intensity profiles, and relative intensity noise.
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4
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Ortega LF, Feigenson T, Tam YW, Reeves-Hall P, Fan TY, Messerly M, Yu CX, Hong KH. 1.2-kW all-fiber Yb-doped multicore fiber amplifier. OPTICS LETTERS 2023; 48:712-714. [PMID: 36723570 DOI: 10.1364/ol.478436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 01/02/2023] [Indexed: 06/18/2023]
Abstract
We have demonstrated a record-high 1.2 kW, all-fiber multicore amplifier using a six-core single-mode Yb-doped fiber and a multicore pump-signal combiner (PSC). The output power is limited by the pump power of 1.9 kW. We have developed double-clad six-core fibers and PSCs for this demonstration. Each of the six Yb-doped cores has a 17-µm mode-field diameter (MFD) with a trench index profile and is capable of kW-class operation. The potential power scaling to the 10-kW level in a single amplifier with high brightness should be feasible with advanced thermal management and coherent beam combination.
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5
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Abstract
Technologies, performances and maturity of ultrafast fiber lasers and fiber delivery of ultrafast pulses are discussed for the medical deployment of laser-wake-field acceleration (LWFA). The compact ultrafast fiber lasers produce intense laser pulses with flexible hollow-core fiber delivery to facilitate electron acceleration in the laser-stimulated wake field near treatment site, empowering endoscopic LWFA brachytherapy. With coherent beam combination of multiple fiber amplifiers, the advantages of ultrafast fiber lasers are further extended to bring in more capabilities in compact LWFA applications.
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6
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Aleshire C, Steinkopff A, Klenke A, Jáuregui C, Kuhn S, Nold J, Haarlammert N, Schreiber T, Limpert J. High-energy Q-switched 16-core tapered rod-type fiber laser system. OPTICS LETTERS 2022; 47:1725-1728. [PMID: 35363718 DOI: 10.1364/ol.454287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/03/2022] [Indexed: 06/14/2023]
Abstract
High-energy Q-switched master oscillator power amplifier systems based on rod-type 4 × 4 multicore fibers are demonstrated, achieving energy up to 49 mJ in ns-class pulses. A tapered fiber geometry is tested that maintains low mode order in large multimode output cores, improving beam quality in comparison to a similar fiber with no taper. The tapered fiber design can be scaled both in the number of amplifying cores and in the dimensions of the cores themselves, providing a potential route toward joule-class fiber lasers systems.
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7
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Wolf AA, Skvortsov MI, Lobach IA, Dostovalov AV, Babin SA. Bending induced output power concentration in a core of a 4-core Yb-doped fiber laser. OPTICS EXPRESS 2022; 30:7580-7590. [PMID: 35299517 DOI: 10.1364/oe.445156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/17/2021] [Indexed: 06/14/2023]
Abstract
An all-fiber 4-core Yb-doped laser with a cavity formed by fiber Bragg gratings directly inscribed in each core with femtosecond laser pulses and 4% Fresnel reflection from the output fiber end face is demonstrated. It has been shown that the diameter of the active fiber winding significantly affects the power distribution between the cores, since it affects both the pump power distribution and the cross-coupling between the cores. In particular, with an active fiber winding diameter of 21 cm, the cores behave independently, and the power is distributed almost evenly over all cores. With a winding diameter of 6.5 cm, the lasing is achieved almost exclusively from one core, and a mechanism of that radiation concentration based on bending induced stress in an active multicore fiber is proposed which explains the experimental data. By analyzing the optical and radio-frequency spectra of the output laser radiation, additional details of the 4-core fiber lasing are revealed. In particular, a narrowband (several longitudinal modes) lasing with periodic linear sweeping of central wavelength in time is observed and characterized in the multicore fiber laser, for the first time to our knowledge. It is shown that crosstalk of longitudinal modes arising from different cores is greatly enhanced in the case of a strongly bent fiber.
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8
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Kalinin NA, Anashkina EA, Leuchs G, Andrianov AV. Lenslet array-free efficient coherent combining of broadband pulses at the output of a multicore fiber with a square core grid. OPTICS EXPRESS 2022; 30:1013-1020. [PMID: 35209246 DOI: 10.1364/oe.446794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 11/29/2021] [Indexed: 06/14/2023]
Abstract
An efficient optical scheme for coherent combining of radiation from the output of a multicore fiber (MCF) with a square array of cores in the out-of-phase supermode is proposed. The scheme uses only simple optical elements and is suitable for an arbitrary number of MCF cores. In a proof-of-concept experiment broadband pulses transmitted through a 25-core fiber were combined with 81% efficiency and good beam quality. In numerical modeling a close to unity efficiency is obtained for a large number of cores. The proposed scheme can be used in a reverse direction for efficient beam splitting and launching the out-of-phase supermode into the MCF.
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9
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Klenke A, Steinkopff A, Aleshire C, Jauregui C, Kuhn S, Nold J, Hupel C, Hein S, Schulze S, Haarlammert N, Schreiber T, Tünnermann A, Limpert J. 500 W rod-type 4 × 4 multicore ultrafast fiber laser. OPTICS LETTERS 2022; 47:345-348. [PMID: 35030602 DOI: 10.1364/ol.445302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 12/10/2021] [Indexed: 06/14/2023]
Abstract
We present a coherently combined femtosecond fiber chirped-pulse-amplification system based on a rod-type, ytterbium-doped, multicore fiber with 4 × 4 cores. A high average power of up to 500 W (after combination and compression) could be achieved at 10 MHz repetition rate with excellent beam quality. Additionally, < 500 fs pulses with up to 600 µJ of pulse energy were also realized with this setup. This architecture is intrinsically power scalable by increasing the number of cores in the fiber.
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Abstract
Fiber laser technology has been demonstrated as a versatile and reliable approach to laser source manufacturing with a wide range of applicability in various fields ranging from science to industry. The power/energy scaling of single-fiber laser systems has faced several fundamental limitations. To overcome them and to boost the power/energy level even further, combining the output powers of multiple lasers has become the primary approach. Among various combining techniques, the coherent beam combining of fiber amplification channels is the most promising approach, instrumenting ultra-high-power/energy lasers with near-diffraction-limited beam quality. This paper provides a comprehensive review of the progress of coherent beam combining for both continuous-wave and ultrafast fiber lasers. The concept of coherent beam combining from basic notions to specific details of methods, requirements, and challenges is discussed, along with reporting some practical architectures for both continuous and ultrafast fiber lasers.
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11
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Controlled Excitation of Supermodes in a Multicore Fiber with a 5 × 5 Square Array of Strongly Coupled Cores. PHOTONICS 2021. [DOI: 10.3390/photonics8080314] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Coherent propagation of supermodes in a multicore fiber is promising for power scaling of fiber laser systems, eliminating the need for the active feedback system to maintain the phases between the channels. We studied the propagation of broadband pulsed radiation at a central wavelength of 1030 nm in a multicore fiber with coupled cores arranged in a square array. We designed and fabricated a silica multicore fiber with a 5 × 5 array of cores. For controllable excitation of a desired supermode, we developed a beam-forming system based on a spatial light modulator. We experimentally measured intensity and phase distributions of the supermodes, in particular, the in-phase and out-of-phase supermodes, which matched well the numerically calculated profiles. We obtained selective excitation and coherent propagation of broadband radiation with the content of the out-of-phase supermode of up to 90% maintained without active feedback. Using three-dimensional numerical modeling with allowance for a refractive index profile similar to those of the developed fiber, we demonstrated stable propagation of the out-of-phase supermode and collapse of the in-phase supermode at a high signal power.
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12
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Balakin AA, Skobelev SA, Andrianov AV, Anashkina EA, Litvak AG. Coherent amplification of high-power laser radiation in multicore fibers from a rectangular array of cores. OPTICS LETTERS 2021; 46:246-249. [PMID: 33448998 DOI: 10.1364/ol.401914] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 12/08/2020] [Indexed: 06/12/2023]
Abstract
The coherent propagation and amplification of high-power laser radiation in a multicore fiber consisting of a square array of weakly bound cores are studied. Exact stable analytical solutions are found for the out-of-phase mode, which describes the coherent propagation of wave beams in such fibers. The analytical results are confirmed by direct numerical simulation of the wave equation. The stability conditions of the out-of-phase mode in the active medium are found.
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13
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Steinkopff A, Jauregui C, Aleshire C, Klenke A, Limpert J. Impact of thermo-optical effects in coherently combined multicore fiber amplifiers. OPTICS EXPRESS 2020; 28:38093-38105. [PMID: 33379629 DOI: 10.1364/oe.410614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 10/28/2020] [Indexed: 06/12/2023]
Abstract
In this work we analyze the power scaling potential of amplifying multicore fibers (MCFs) used in coherently combined systems. In particular, in this study we exemplarily consider rod-type MCFs with 2 × 2 up to 10 × 10 ytterbium-doped cores arranged in a squared pattern. We will show that, even though increasing the number of active cores will lead to higher output powers, particular attention has to be paid to arising thermal effects, which potentially degrade the performance of these systems. Additionally, we analyze the influence of the core dimensions on the extractable and combinable output power and pulse energy. This includes a detailed study on the thermal effects that influence the propagating transverse modes and, in turn, the amplification efficiency, the combining efficiency, the onset of nonlinear effect, as well as differences in the optical path lengths between the cores. Considering all these effects under rather extreme conditions, the study predicts that average output powers higher than 10 kW from a single 1 m long ytterbium-doped MCF are feasible and femtosecond pulses with energies higher than 400 mJ can be extracted and efficiently recombined in a filled-aperture scheme.
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14
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Lin D, Carpenter J, Feng Y, Jain S, Jung Y, Feng Y, Zervas MN, Richardson DJ. Reconfigurable structured light generation in a multicore fibre amplifier. Nat Commun 2020; 11:3986. [PMID: 32778643 PMCID: PMC7417554 DOI: 10.1038/s41467-020-17809-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 07/16/2020] [Indexed: 01/10/2023] Open
Abstract
Structured light, with spatially varying phase or polarization distributions, has given rise to many novel applications in fields ranging from optical communication to laser-based material processing. However the efficient and flexible generation of such beams from a compact laser source at practical output powers still remains a great challenge. Here we describe an approach capable of addressing this need based on the coherent combination of multiple tailored Gaussian beams emitted from a multicore fibre (MCF) amplifier. We report a proof-of-concept structured light generation experiment, using a cladding-pumped 7-core MCF amplifier as an integrated parallel amplifier array and a spatial light modulator (SLM) to actively control the amplitude, polarization and phase of the signal light input to each fibre core. We report the successful generation of various structured light beams including high-order linearly polarized spatial fibre modes, cylindrical vector (CV) beams and helical phase front optical vortex (OV) beams.
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Affiliation(s)
- Di Lin
- Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK.
| | - Joel Carpenter
- School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Yutong Feng
- Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK
| | - Saurabh Jain
- Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK
| | - Yongmin Jung
- Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK
| | - Yujun Feng
- Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK
| | - Michalis N Zervas
- Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK
| | - David J Richardson
- Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK
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Aleshire C, Steinkopff A, Jauregui C, Klenke A, Tünnermann A, Limpert J. Simplified design of optical elements for filled-aperture coherent beam combination. OPTICS EXPRESS 2020; 28:21035-21045. [PMID: 32680151 DOI: 10.1364/oe.394084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 05/13/2020] [Indexed: 06/11/2023]
Abstract
A simplification strategy for segmented mirror splitters (SMS) used as beam combiners is presented. These devices are useful for compact beam division and the combination of linear and 2-D arrays. However, the standard design requires unique thin-film coating sections for each input beam; thus, potential for scaling to high beam-counts is limited due to manufacturing complexity. Taking advantage of the relative insensitivity of the beam combination process to amplitude variations, numerical techniques are used to optimize highly simplified designs with only one, two or three unique coatings. It is demonstrated that with correctly chosen coating reflectivities, the simplified optics are capable of high combination efficiency for several tens of beams. The performance of these optics as beam splitters in multicore fiber amplifier systems is analyzed, and inhomogeneous power distribution of the simplified designs is noted as a potential source of combining loss in such systems. These simplified designs may facilitate further scaling of filled-aperture coherently combined systems in linear array or 2-D array formats.
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16
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Ren Z, Fu Q, Xu L, Price JHV, Alam SU, Richardson DJ. Compact, high repetition rate, 4.2 MW peak power, 1925 nm, thulium-doped fiber chirped-pulse amplification system with dissipative soliton seed laser. OPTICS EXPRESS 2019; 27:36741-36749. [PMID: 31873447 DOI: 10.1364/oe.27.036741] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 11/04/2019] [Indexed: 06/10/2023]
Abstract
We report the demonstration of a high average- and peak-power, 1925 nm, thulium-fiber based chirped pulse amplification (CPA) system. A compact, dissipative soliton thulium-fiber, mode-locked seed produced pre-chirped pulses with 25 ps duration, 45 mW output power and repetition rate of 15.7 MHz. After stretching to 105 ps in 83 m of normal dispersion fiber, the pulses were amplified in a core-pumped pre-amplifier and a cladding pumped power amplifier to average output powers of 28 W and 30 W with forward and backward pumping, respectively, with the output power limited only by the available pump power. After a pair of fused silica transmission gratings with an efficiency of 71%, the amplified pulses were re-compressed to 297 fs yielding pulses with a peak power of 4.2 MW (backward pumped) and a pulse energy of 1.27 µJ.
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Heilmann A, Le Dortz J, Daniault L, Fsaifes I, Bellanger S, Bourderionnet J, Larat C, Lallier E, Antier M, Durand E, Simon-Boisson C, Brignon A, Chanteloup JC. Coherent beam combining of seven fiber chirped-pulse amplifiers using an interferometric phase measurement. OPTICS EXPRESS 2018; 26:31542-31553. [PMID: 30650738 DOI: 10.1364/oe.26.031542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 10/06/2018] [Indexed: 06/09/2023]
Abstract
Coherent beam combining in tiled-aperture configuration is demonstrated on seven femtosecond fiber amplifiers using an interferometric phase measurement technique. The residual phase error between two fibers is as low as λ/55 RMS and a combination efficiency of 48% has been achieved. The combined pulses are compressed to 216 fs, delivering 71 W average power at a repetition rate of 55 MHz. Operating the laser system in a nonlinear regime with an estimated B-integral of 5 rad yields a combining efficiency of 45% with the same phase stability. These results pave the way to very large high-power and high energy coherent beam combining systems.
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18
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Lægsgaard J, Poli F, Cucinotta A, Selleri S. Theory of thermo-optic instabilities in dual-core fiber amplifiers. OPTICS LETTERS 2018; 43:4775-4778. [PMID: 30272737 DOI: 10.1364/ol.43.004775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 09/01/2018] [Indexed: 06/08/2023]
Abstract
A coupled-mode theory for nonlinear mode coupling by the thermo-optic effect, originally developed for single-core fiber amplifiers, is applied to the case of dual-core amplifiers. It is shown that a non-phase-matched coupling term, which is usually irrelevant in single-core amplifiers, can strongly affect the mode stability when the coupling length between supermodes exceeds a few centimeters. The phase-mismatched coupling can lead to a strongly reduced instability threshold and static deformation effects for a range of intermediate coupling lengths.
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