1
|
Leventoux Y, Granger G, Arosa Y, Tilouine I, Krupa K, Tonello A, Couderc V, Février S. Three octave visible to mid-infrared supercontinuum generation seeded by multimode silica fiber pumped at 1064 nm. OPTICS LETTERS 2023; 48:4582-4585. [PMID: 37656560 DOI: 10.1364/ol.497678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 08/04/2023] [Indexed: 09/03/2023]
Abstract
Hyperspectral spectroscopy requires light sources with wide spectral ranges from the visible to the mid-infrared. Here, we demonstrate the first fiber-based mid-infrared supercontinuum covering three octaves of frequency by leveraging 1-µm laser technology. The process consists in spectral broadening of a 1064-nm pump toward 0.48-2.5 µm in a graded-index multimode fiber, followed by a fluoro-indate fiber used to reach deeper into the near infrared (4.3 µm). Finally, an arsenic selenide chalcogenide fiber allows us to reach the 6-µm wavelength region, providing a 0.75-6-µm supercontinuum. We illustrate the potential of this light source by recording mid-infrared absorption spectra of organic compounds.
Collapse
|
2
|
Agrawal GP. Spatial beam narrowing in multimode graded-index fiber amplifiers: an analytic approach. OPTICS LETTERS 2023; 48:259-262. [PMID: 36638432 DOI: 10.1364/ol.479060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Accepted: 12/01/2022] [Indexed: 06/17/2023]
Abstract
Doped and optically pumped graded-index (GRIN) fibers can be used to amplify an optical beam such that its spatial quality is improved at the output end of the fiber compared with that of the unamplified beam. We develop a simple model of the amplification process in such GRIN fiber amplifiers and show that the resulting equations can be solved analytically with suitable approximations. The solution shows that the width of the amplifying beam oscillates but also becomes narrower because of the radial dependence of the optical gain. The main advantage of our simplified approach is that it provides an analytic expression for the damping distance of beam-width oscillations that shows clearly the role played by various physical parameters.
Collapse
|
3
|
Sidelnikov OS, Podivilov EV, Fedoruk MP, Kuznetsov AG, Wabnitz S, Babin SA. Mechanism of brightness enhancement in multimode LD-pumped graded-index fiber Raman lasers: numerical modeling. OPTICS EXPRESS 2022; 30:8212-8221. [PMID: 35299567 DOI: 10.1364/oe.449773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 01/21/2022] [Indexed: 06/14/2023]
Abstract
We develop a comprehensive theory for describing the experimental beam profiles from multimode fiber Raman lasers. We take into account the presence of random linear mode coupling, Kerr beam self-cleaning and intra-cavity spatial filtering. All of these factors play a decisive role in shaping the Stokes beam, which has a predominant fundamental mode content. Although the highly multimode pump beam is strongly depleted, it remains almost insensitive to the different physical effects. As a result, the intensity of the output Stokes beam is an order of magnitude higher than the pump intensity at its maximum, in quantitative agreement with the experimental results and in contrast with the simplified balance model.
Collapse
|
4
|
Spatio-spectral beam control in multimode diode-pumped Raman fibre lasers via intracavity filtering and Kerr cleaning. Sci Rep 2021; 11:21994. [PMID: 34754003 PMCID: PMC8578583 DOI: 10.1038/s41598-021-01491-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 10/22/2021] [Indexed: 12/01/2022] Open
Abstract
Multimode fibres provide a promising platform for boosting the capacity of fibre links and the output power of fibre lasers. The complex spatiotemporal dynamics of multimode beams may be controlled in spatial and temporal domains via the interplay of nonlinear, dispersive and dissipative effects. Raman nonlinearity induces beam cleanup in long graded-index fibres within a laser cavity, even for CW Stokes beams pumped by highly-multimode laser diodes (LDs). This leads to a breakthrough approach for wavelength-agile high-power lasers. However, current understanding of Raman beam cleanup is restricted to a small-signal gain regime, being not applicable to describing realistic laser operation. We solved this challenge by experimentally and theoretically studying pump-to-Stokes beam conversion in a graded-index fibre cavity. We show that random mode coupling, intracavity filtering and Kerr self-cleaning all play a decisive role for the spatio-spectral control of CW Stokes beams. Whereas the depleted LD pump radiation remains insensitive to them.
Collapse
|
5
|
Fan C, Xiao H, Yao T, Xu J, Chen Y, Leng J, Zhou P. Kilowatt level Raman amplifier based on 100 µm core diameter multimode GRIN fiber with M 2 = 1.6. OPTICS LETTERS 2021; 46:3432-3435. [PMID: 34264231 DOI: 10.1364/ol.431273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 06/07/2021] [Indexed: 06/13/2023]
Abstract
In this Letter, we demonstrate a high-power Raman fiber amplifier with excellent beam quality based on graded-index fiber. The Yb-doped fiber laser (YDFL) and bandwidth-tunable amplified spontaneous emission (ASE) source are employed as the pump source to compare the laser performance separately. When the ASE with a bandwidth of 8 nm is employed, a maximum power of 943 W at 1130 nm is achieved, which is twice that pumped by YDFL. The beam quality factor M2 at maximum output power is 1.6, with a brightness enhancement (BE) factor of 27. To the best of our knowledge, this is the best beam quality and BE factor based on pure Raman gain with output power of over 100 W.
Collapse
|
6
|
Fan C, Chen Y, Yao T, Xiao H, Xu J, Leng J, Zhou P, Wolf AA, Nemov IN, Kuznetsov AG, Kablukov SI, Babin SA. Over 400 W graded-index fiber Raman laser with brightness enhancement. OPTICS EXPRESS 2021; 29:19441-19449. [PMID: 34266053 DOI: 10.1364/oe.427605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 06/01/2021] [Indexed: 06/13/2023]
Abstract
The power scaling on all-fiberized Raman fiber oscillator with brightness enhancement (BE) based on multimode graded-index (GRIN) fiber is demonstrated. Thanks to beam cleanup of GRIN fiber itself and single-mode selection properties of the fiber Bragg gratings inscribed in the center of GRIN fiber, the efficient BE is realized. For the laser cavity with single OC FBG, continuous-wave power of 334 W with an M2 value of 2.8 and BE value of 5.6 were obtained at a wavelength of 1120 nm with an optical-to-optical efficiency of 49.6%. Furthermore, the cavity reflectivity is increased by employing two OC FBGs to scale the output power up to 443 W, while the corresponding M2 is 3.5 with BE of 4.2. To our best knowledge, it is the highest power in Raman oscillator based on GRIN fiber.
Collapse
|
7
|
Kuznetsov AG, Nemov IN, Wolf AA, Kablukov SI, Babin SA. Multimode LD-pumped all-fiber Raman laser with excellent quality of 2 nd-order Stokes output beam at 1019 nm. OPTICS EXPRESS 2021; 29:17573-17580. [PMID: 34154297 DOI: 10.1364/oe.425639] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 05/03/2021] [Indexed: 06/13/2023]
Abstract
A multimode all-fiber Raman laser enabling cascaded generation of high-quality 1019-nm output beam at direct pumping by highly-multimode (M2>30) 940-nm laser diodes has been demonstrated. The laser is made of a 100/140 graded-index fiber with special in-fiber Bragg gratings which secure sequential generation of the 1st (976 nm) and 2nd (1019 nm) Stokes orders. Comparing different 1019-nm cavity structures shows that the half-open cavity with one FBG and distributed feedback via random Rayleigh backscattering provides excellent quality (M2∼1.3) with higher slope efficiency of pump-to-2nd Stokes conversion than in the conventional 2-FBG cavity. The maximum achieved slope efficiency amounts to about 40% at output powers of up to 12 W limited by the 3rd Stokes generation.
Collapse
|
8
|
Liu N, Su J, Liu Y, Li J, Li X. Temporal mode properties of Raman scattering in optical fibers. OPTICS EXPRESS 2021; 29:13408-13415. [PMID: 33985074 DOI: 10.1364/oe.421222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/10/2021] [Indexed: 06/12/2023]
Abstract
By investigating the intensity correlation function, we study the temporal mode properties of spontaneous Raman photons generated in single mode fibers pumped by short pulses. We find that the intensity correlation function of the Raman photons is related to the dispersion induced temporal mismatch among the Raman photons generated in different subparts of the fiber. When no temporal mismatch exists, the intensity correlation function only depends on the ratio between the pulse width of the pump and the coherence time of the Raman photons. With the ratio decreasing, the intensity correlation function increase. Our study is helpful for easily creating high-quality true thermal light which will be a useful resource for second-order coherence based remote sensing.
Collapse
|
9
|
Abstract
We experimentally demonstrate the spatial self-cleaning of a highly multimode optical beam, in the process of second-harmonic generation in a quadratic nonlinear potassium titanyl phosphate crystal. As the beam energy grows larger, the output beam from the crystal evolves from a highly speckled intensity pattern into a single, bell-shaped spot, sitting on a low energy background. We demonstrate that quadratic beam cleanup is accompanied by significant self-focusing of the fundamental beam, for both positive and negative signs of the linear phase mismatch close to the phase-matching condition.
Collapse
|
10
|
Chen Y, Yao T, Xiao H, Leng J, Zhou P. High-power cladding pumped Raman fiber amplifier with a record beam quality. OPTICS LETTERS 2020; 45:2367-2370. [PMID: 32287234 DOI: 10.1364/ol.388297] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 03/23/2020] [Indexed: 06/11/2023]
Abstract
In this Letter, a high-power, high-brightness all-fiberized Raman amplifier based on a cladding-pumping scheme is presented for the first time, to the best of our knowledge. The triple-clad passive fiber is employed as Raman gain fiber in the laser system. The maximum output power is 762.6 W emitting at 1130 nm. To the best of our knowledge, this is the highest power in the fields of cladding-pumped Raman amplifiers. Through a cladding-pumping process, the beam quality parameter ${{\rm M}^2}$M2 improves from 6.12 of seed laser to 2.24 at maximum output power of 762.6 W, while the best ${{\rm M}^2}$M2 is 1.9 at 267.2 W. It is also the best beam quality of Raman laser with brightness enhancement in any kind of configuration (graded-index fiber or multi-clad fiber, laser or amplifier, all-fiber or free-space configuration) with power of over 100 W.
Collapse
|
11
|
Zhang B, Ma S, He Q, Guo J, Jiao Z, Wang B. Investigation on saturable absorbers based on nonlinear Kerr beam cleanup effect. OPTICS EXPRESS 2020; 28:6367-6377. [PMID: 32225886 DOI: 10.1364/oe.384376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 02/12/2020] [Indexed: 06/10/2023]
Abstract
We experimentally investigate characteristics of saturable absorbers (SAs) based on nonlinear Kerr beam cleanup effect (NL-KBC). The SAs are formed by a long graded-index multimode fiber (GRIN MMF) with a short single-mode fiber served as a diaphragm. We studied the evolution of output spectrum and beam profiles from the GRIN MMF in order to investigate the mechanism of these SAs. We further performed saturable absorption measurements to evaluate their modulation depths and saturation intensities. We experimentally observed and first theoretically analyzed the "relaxation oscillation" behavior of the optical transmittance with increasing input intensity. We also studied their nonlinear polarization dynamics and observed the repolarized effect in NL-KBC regime. Our results confirm the optical properties of the SAs based on NL-KBC, and these SAs can find applications in Q-switched and mode-locked lasers.
Collapse
|
12
|
Liu C, Liang Y, Wang L. Single-shot photoacoustic microscopy of hemoglobin concentration, oxygen saturation, and blood flow in sub-microseconds. PHOTOACOUSTICS 2020; 17:100156. [PMID: 31956486 PMCID: PMC6957791 DOI: 10.1016/j.pacs.2019.100156] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 11/28/2019] [Accepted: 12/05/2019] [Indexed: 05/04/2023]
Abstract
We present fast functional optical-resolution photoacoustic microscopy (OR-PAM) that can simultaneously image hemoglobin concentration, blood flow speed, and oxygen saturation with three-pulse excitation. To instantaneously determine the blood flow speed, dual-pulse photoacoustic flowmetry is developed to determine the blood flow speed from photoacoustic signal decay in sub-microseconds. Grueneisen relaxation effect is compensated for in the oxygen saturation calculation. The blood flow imaging is validated in phantom and in vivo experiments. The results show that the flow speed can be measured accurately in sub-microseconds by comparing the dual-pulse flowmetric method with photoacoustic Doppler flowmetry. Wide-field OR-PAM of hemoglobin concentration, blood flow speed, and oxygen saturation are demonstrated in the mouse ear. This technical advance enables more biomedical applications for fast functional OR-PAM.
Collapse
Affiliation(s)
- Chao Liu
- Department of Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Ave., Kowloon, Hong Kong, China
- City University of Hong Kong Shenzhen Research Institute, Yuexing Yi Dao, Nanshan District, Shenzhen, Guang Dong, 518057, China
| | - Yizhi Liang
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
- Corresponding author.
| | - Lidai Wang
- Department of Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Ave., Kowloon, Hong Kong, China
- City University of Hong Kong Shenzhen Research Institute, Yuexing Yi Dao, Nanshan District, Shenzhen, Guang Dong, 518057, China
- Corresponding author at: Department of Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Ave., Kowloon, Hong Kong, China.
| |
Collapse
|
13
|
Chen Y, Yao T, Huang L, Xiao H, Leng J, Zhou P. 2 kW high-efficiency Raman fiber amplifier based on passive fiber with dynamic analysis on beam cleanup and fluctuation. OPTICS EXPRESS 2020; 28:3495-3504. [PMID: 32122016 DOI: 10.1364/oe.383683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 01/15/2020] [Indexed: 06/10/2023]
Abstract
In this paper, we study the power scaling in high power continuous-wave Raman fiber amplifier employing graded-index passive fiber. The maximum output power reaches 2.087 kW at 1130 nm with an optical conversion efficiency of 90.1% (the output signal power versus the depleted pump power). To the best of our knowledge, this is the highest power in the fields of Raman fiber lasers based merely on Stokes radiation. The beam quality parameter M2 improves from 15 to 8.9 during the power boosting process, then beam spot distortion appears at high power level. This is the first observation and analysis on erratic dynamic properties of the transverse modes in high power Raman fiber amplifier.
Collapse
|
14
|
Kuznetsov AG, Evmenova EA, Dontsova EI, Kablukov SI, Babin SA. Frequency doubling of multimode diode-pumped GRIN-fiber Raman lasers. OPTICS EXPRESS 2019; 27:34760-34768. [PMID: 31878659 DOI: 10.1364/oe.27.034760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 10/16/2019] [Indexed: 06/10/2023]
Abstract
Frequency doubling of multimode diode-pumped GRIN-fiber Raman laser with improved beam quality (M2=1.9-2.6 depending on configuration) in a simple single-pass scheme with 5-mm PPLN crystal is studied. After scheme optimization and elimination of back reflection and crystal heating effects, an efficient conversion into blue spectral range with output power of about 0.4 W@488 nm and 0.64 W@477 nm has been demonstrated.
Collapse
|
15
|
Wang J, Ding X, Liu J, Zhang G, Yu X, Sun B, Liu Y, Li T, Bai Y, Zhao L, Jiang G, Lei P, Wu L, Yao J. Evolution of the Raman beam quality in a folded-coupled-cavity Nd:YVO 4/YVO 4 Raman laser. APPLIED OPTICS 2019; 58:8785-8790. [PMID: 31873655 DOI: 10.1364/ao.58.008785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 10/14/2019] [Indexed: 06/10/2023]
Abstract
An end-pumped actively $Q$Q-switched ${\rm Nd}\!:\!{{\rm YVO}_4}/{{\rm YVO}_4}$Nd:YVO4/YVO4 Raman laser with a folded coupled cavity is demonstrated to study the evolution of Raman beam quality. The theoretical mechanism of the beam cleanup effect of stimulated Raman scattering is analyzed. The beam quality ($M^2$M2) of the Raman beam and the fundamental beams before and after the Raman conversion are measured experimentally. The results show that with the incident pump power increasing, the ${M^2}$M2 of the fundamental beam increases from 1.85 to 3.08, while the ${M^2}$M2 of the Raman beam increases from 1.21 to 1.69. The beam quality of the Raman laser and its degradation are better than that of the fundamental laser.
Collapse
|
16
|
Evmenova EA, Kuznetsov AG, Nemov IN, Wolf AA, Dostovalov AV, Kablukov SI, Babin SA. 2nd-order random lasing in a multimode diode-pumped graded-index fiber. Sci Rep 2018; 8:17495. [PMID: 30504776 PMCID: PMC6269461 DOI: 10.1038/s41598-018-35767-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 11/09/2018] [Indexed: 11/09/2022] Open
Abstract
Raman lasing in a graded-index fiber (GIF) attracts now great deal of attention due to the opportunity to convert high-power multimode laser diode radiation into the Stokes wave with beam quality improvement based on the Raman clean-up effect. Here we report on the cascaded Raman generation of the 2nd Stokes order in the 1.1-km long GIF with 100-μm core directly pumped by 915-nm diodes. In the studied all-fiber scheme, the 1st Stokes order is generated at 950-954 nm in a linear cavity formed at GIF ends by two fiber Bragg gratings (FBGs) securing beam quality improvement from M2 ≈ 30 to M2 ≈ 2.3 due to special transverse structure of FBGs. The 2nd Stokes wave is generated either in linear (two FBGs) or half-open (one FBG) cavity with random distributed feedback via Rayleigh backscattering. Their comparison shows that the random lasing provides better beam quality and higher slope efficiency. Nearly diffraction limited beam (M2 ≈ 1.6) with power up to 27 W at maximum gain (996 nm), and 17 W at the detuned wavelength of 978 nm has been obtained, thus demonstrating that the 2nd-order random lasing in diode-pumped GIF with FBGs provides high-efficiency high-quality beam generation in a broad wavelength range within the Raman gain spectral profile.
Collapse
Affiliation(s)
| | - Alexey G Kuznetsov
- Institute of Automation and Electrometry SB RAS, Novosibirsk, 630090, Russia
| | - Ilya N Nemov
- Institute of Automation and Electrometry SB RAS, Novosibirsk, 630090, Russia
| | - Alexey A Wolf
- Institute of Automation and Electrometry SB RAS, Novosibirsk, 630090, Russia
- Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Alexandr V Dostovalov
- Institute of Automation and Electrometry SB RAS, Novosibirsk, 630090, Russia
- Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Sergey I Kablukov
- Institute of Automation and Electrometry SB RAS, Novosibirsk, 630090, Russia
- Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Sergey A Babin
- Institute of Automation and Electrometry SB RAS, Novosibirsk, 630090, Russia.
- Novosibirsk State University, Novosibirsk, 630090, Russia.
| |
Collapse
|
17
|
Lægsgaard J. Spatial beam cleanup by pure Kerr processes in multimode fibers. OPTICS LETTERS 2018; 43:2700-2703. [PMID: 29856371 DOI: 10.1364/ol.43.002700] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 05/02/2018] [Indexed: 06/08/2023]
Abstract
Recent experiments with pulse propagation in multimode graded-index fibers have shown a nonlinear improvement in beam quality, even in situations where dissipative processes such as Raman scattering play no significant role. In this Letter, numerical simulations of beam cleanup by third-order Kerr nonlinearities in a multimode fiber are used to demonstrate that in the absence of dissipative processes beam cleanup is crucially dependent on spectral/temporal disorder and does not occur in a continuous-wave model. This finding is in accordance with fundamental considerations on entropy.
Collapse
|
18
|
Glick Y, Shamir Y, Wolf AA, Dostovalov AV, Babin SA, Pearl S. Highly efficient all-fiber continuous-wave Raman graded-index fiber laser pumped by a fiber laser. OPTICS LETTERS 2018; 43:1027-1030. [PMID: 29489772 DOI: 10.1364/ol.43.001027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 01/24/2018] [Indexed: 06/08/2023]
Abstract
We report for the first time, to the best of our knowledge, an all-fiber Raman graded-index (GRIN) fiber laser pumped by a fiber laser. This configuration points to potential future power and brightness increases. Continuous-wave power of 135 W with an M2 value of 2.5 was obtained at a wavelength of 1081 nm with an optical-to-optical efficiency of 68%. A commercial GRIN core fiber acts as the Raman fiber in a power oscillator configuration that includes fiber Bragg gratings (FBGs) written onto the GRIN fiber. The efficiency and brightness demonstrated here are, to the best of our knowledge, the highest reported in any Raman GRIN fiber laser. A brightness enhancement of the pump beam by a factor of 5.6 is attained due to the transverse profiles of Raman gain and FBG reflection in the GRIN fiber.
Collapse
|
19
|
Dupiol R, Krupa K, Tonello A, Fabert M, Modotto D, Wabnitz S, Millot G, Couderc V. Interplay of Kerr and Raman beam cleaning with a multimode microstructure fiber. OPTICS LETTERS 2018; 43:587-590. [PMID: 29400847 DOI: 10.1364/ol.43.000587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 12/27/2017] [Indexed: 06/07/2023]
Abstract
We experimentally study the competition between Kerr beam self-cleaning and Raman beam cleanup in a multimode air-silica microstructure optical fiber. Kerr beam self-cleaning of the pump is observed for a certain range of input powers only. Stokes Raman beam generation and cleanup lead to both depletion and degradation of beam quality for the pump. The interplay of modal four-wave mixing and Raman scattering in the infrared domain leads to the generation of a multimode supercontinuum ranging from 500 nm up to 1800 nm.
Collapse
|
20
|
Guenard R, Krupa K, Dupiol R, Fabert M, Bendahmane A, Kermene V, Desfarges-Berthelemot A, Auguste JL, Tonello A, Barthélémy A, Millot G, Wabnitz S, Couderc V. Nonlinear beam self-cleaning in a coupled cavity composite laser based on multimode fiber. OPTICS EXPRESS 2017; 25:22219-22227. [PMID: 29041536 DOI: 10.1364/oe.25.022219] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 07/26/2017] [Indexed: 05/24/2023]
Abstract
We study a coupled cavity laser configuration where a passively Q-switched Nd:YAG microchip laser is combined with an extended cavity, including a doped multimode fiber. For appropriate coupling levels with the extended cavity, we observed that beam self-cleaning was induced in the multimode fiber thanks to nonlinear modal coupling, leading to a quasi-single mode laser output. In the regime of beam self-cleaning, laser pulse duration was reduced from 525 to 225 ps. We also observed a Q-switched mode-locked operation, where spatial self-cleaning was accompanied by far-detuned nonlinear frequency conversion in the active multimode fiber.
Collapse
|
21
|
Zlobina EA, Kablukov SI, Wolf AA, Nemov IN, Dostovalov AV, Tyrtyshnyy VA, Myasnikov DV, Babin SA. Generating high-quality beam in a multimode LD-pumped all-fiber Raman laser. OPTICS EXPRESS 2017; 25:12581-12587. [PMID: 28786613 DOI: 10.1364/oe.25.012581] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 05/06/2017] [Indexed: 06/07/2023]
Abstract
We report on the first demonstration of an all-fiber CW Raman laser based on a multimode graded-index fiber directly pumped by multimode fiber-coupled laser diodes. A joint action of Raman clean-up effect and mode-selection properties of special fiber Bragg gratings inscribed in the central part of the graded-index fiber core, results in high-efficiency conversion of a multimode (M2~26) pump at 915 nm into a high-quality (M2~2.6) output beam at 954 nm. About 50 W output power has been obtained with slope efficiency of 67%. The proposed development and integration of key multimode fiber technologies opens the door to new type of LD-pumped high-power high-beam-quality fiber lasers that may operate at almost any wavelength defined by available LDs.
Collapse
|
22
|
Guenard R, Krupa K, Dupiol R, Fabert M, Bendahmane A, Kermene V, Desfarges-Berthelemot A, Auguste JL, Tonello A, Barthélémy A, Millot G, Wabnitz S, Couderc V. Kerr self-cleaning of pulsed beam in an ytterbium doped multimode fiber. OPTICS EXPRESS 2017; 25:4783-4792. [PMID: 28380747 DOI: 10.1364/oe.25.004783] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We experimentally demonstrate that Kerr spatial self-cleaning of a pulsed beam can be obtained in an amplifying multimode optical fiber. An input peak power of 500 W only was sufficient to produce a quasi-single-mode emission from the double-clad ytterbium doped multimode fiber (YMMF) with non-parabolic refractive index profile. We compare the self-cleaning behavior observed in the same fiber with loss and with gain. Laser gain introduces new opportunities to achieve spatial self-cleaning of light in multimode fibers at a relatively low power threshold.
Collapse
|
23
|
Glick Y, Fromzel V, Zhang J, Ter-Gabrielyan N, Dubinskii M. High-efficiency, 154 W CW, diode-pumped Raman fiber laser with brightness enhancement. APPLIED OPTICS 2017; 56:B97-B102. [PMID: 28157871 DOI: 10.1364/ao.56.000b97] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We demonstrate a high-power, high-efficiency Raman fiber laser pumped directly by laser diode modules at 978 nm. 154 W of CW power were obtained at a wavelength of 1023 nm with an optical to optical efficiency of 65%. A commercial graded-index (GRIN) core fiber acts as the Raman fiber in a power oscillator configuration, which includes spectral selection to prevent generation of the second Stokes. In addition, brightness enhancement of the pump beam by a factor of 8.4 is attained due to the Raman gain distribution profile in the GRIN fiber. To the best of our knowledge this is the highest power and highest efficiency Raman fiber laser demonstrated in any configuration allowing brightness enhancement (i.e., in either cladding-pumped configuration or with GRIN fibers, excluding step-index core pumped), regardless of pumping scheme (i.e., either diode pumped or fiber laser pumped).
Collapse
|
24
|
Zlobina EA, Kablukov SI, Wolf AA, Dostovalov AV, Babin SA. Nearly single-mode Raman lasing at 954 nm in a graded-index fiber directly pumped by a multimode laser diode. OPTICS LETTERS 2017; 42:9-12. [PMID: 28059211 DOI: 10.1364/ol.42.000009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
High beam quality and narrow spectrum have been obtained in a Raman fiber laser based on a 1.1 km long graded-index fiber directly pumped by a multimode 915 nm laser diode. The generation of a near-diffraction-limited beam at 954 nm with M2≤1.27 and Δλ=0.42 nm at an output power above 10 W is enabled by a cavity mirror made of a special fiber Bragg grating inscribed by a femtosecond technique in the central part of the graded-index fiber core.
Collapse
|
25
|
Buma T, Farland JL, Ferrari MR. Near-infrared multispectral photoacoustic microscopy using a graded-index fiber amplifier. PHOTOACOUSTICS 2016; 4:83-90. [PMID: 27761407 PMCID: PMC5063359 DOI: 10.1016/j.pacs.2016.08.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 08/08/2016] [Accepted: 08/11/2016] [Indexed: 05/22/2023]
Abstract
We demonstrate optical resolution photoacoustic microscopy (OR-PAM) of lipid-rich tissue using a multi-wavelength pulsed laser based on nonlinear fiber optics. 1047 nm laser pulses are converted to 1098, 1153, 1215, and 1270 nm pulses via stimulated Raman scattering in a graded-index multimode fiber. Multispectral PAM of a lipid phantom is demonstrated with our low-cost and simple technique.
Collapse
Affiliation(s)
- Takashi Buma
- Department of Electrical and Computer Engineering, Union College, Schenectady, NY 12308, USA
- Bioengineering Program, Union College, Schenectady, NY 12308, USA
- Corresponding author at: Department of Electrical and Computer Engineering, Union College, Schenectady, NY 12308, USA.
| | | | | |
Collapse
|
26
|
Liu Z, Wright LG, Christodoulides DN, Wise FW. Kerr self-cleaning of femtosecond-pulsed beams in graded-index multimode fiber. OPTICS LETTERS 2016; 41:3675-8. [PMID: 27519060 DOI: 10.1364/ol.41.003675] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We observe a nonlinear spatial self-cleaning process for femtosecond pulses in graded-index (GRIN) multimode fiber (MMF). Pulses with ∼80 fs duration at 1030 nm are launched into GRIN MMF with 62.5 μm core. The near-field beam profile at the output end of the fiber evolves from a speckled pattern to a centered, bell-shaped transverse structure with increasing pulse energy. The experimental observations agree well with numerical simulations, which show that the Kerr nonlinearity underlies the process. This self-cleaning process may find applications in ultrafast pulse generation and beam-combining.
Collapse
|
27
|
Liu J, Yao W, Zhao C, Shen D, Fan D. Volume Bragg grating narrowed high-power and highly efficient cladding-pumped Raman fiber laser. APPLIED OPTICS 2014; 53:8256-8260. [PMID: 25608067 DOI: 10.1364/ao.53.008256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
High-power and highly efficient operation of a single-mode cladding-pumped Raman fiber laser with narrow lasing bandwidth is demonstrated. The spectral narrowing was realized by an external cavity containing a volume Bragg grating with a center wavelength of 1658 nm. A maximum output power of 10.4 W at 1658.3 nm with a spectral linewidth (FWHM) of ∼0.1 nm was obtained for the launched pump power of 18.4 W, corresponding to a slope efficiency of 109% with respect to the launched pump power. Lasing characteristics of free-running operation are also evaluated and discussed.
Collapse
|
28
|
Liu J, Shen D, Huang H, Zhao C, Zhang X, Fan D. High-power and highly efficient operation of wavelength-tunable Raman fiber lasers based on volume Bragg gratings. OPTICS EXPRESS 2014; 22:6605-6612. [PMID: 24664009 DOI: 10.1364/oe.22.006605] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Highly efficient and high-power operation of Raman fiber lasers in fixed-wavelength and wavelength-tunable cavity configurations based on a graded-index multimode fiber is reported. Fixed-wavelength and wavelength tunable operating regimes are achieved using volume Bragg gratings (VBGs) with center wavelengths of 1658 nm and 1750 nm, respectively. The fixed-wavelength laser yielded a maximum output power of 10.5 W at 1658.3 nm with a FWHM linewidth of ~0.1 nm for the launched pump power of 23.4 W, corresponding to a slope efficiency of 82.7% with respect to the launched pump power. The measured beam quality in the form of M² factor is ~1.35, corresponding to the fundamental mode of the fiber. For the wavelength-tunable Raman fiber laser, a wavelength tuning range of 37 nm from 1638.5 to 1675.1 nm is obtained with a maximum output power of 3.6 W at 1658.5 nm for the launched pump power of 13.0 W.
Collapse
|
29
|
Manninen A, Kääriäinen T, Parviainen T, Buchter S, Heiliö M, Laurila T. Long distance active hyperspectral sensing using high-power near-infrared supercontinuum light source. OPTICS EXPRESS 2014; 22:7172-7177. [PMID: 24664065 DOI: 10.1364/oe.22.007172] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A hyperspectral remote sensing instrument employing a novel near-infrared supercontinuum light source has been developed for active illumination and identification of targets. The supercontinuum is generated in a standard normal dispersion multi-mode fiber and has 16 W total optical output power covering 1000 nm to 2300 nm spectral range. A commercial 256-channel infrared spectrometer was used for broadband infrared detection. The feasibility of the presented hyperspectral measurement approach was investigated both indoors and in the field. Reflection spectra from several diffusive targets were successfully measured and a measurement range of 1.5 km was demonstrated.
Collapse
|
30
|
Babin SA, Dontsova EI, Kablukov SI. Random fiber laser directly pumped by a high-power laser diode. OPTICS LETTERS 2013; 38:3301-3303. [PMID: 23988940 DOI: 10.1364/ol.38.003301] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A random lasing based on Rayleigh scattering (RS) in a passive fiber directly pumped by a high-power laser diode (LD) has been demonstrated. Owing to the RS-based random distributed feedback (RDFB) the low-quality LD beam (938 nm) is converted into the high-quality laser output (980 nm). Because of the relatively low excess above the threshold with the available LD, the RDFB laser output is not stationary and limited in power at the 0.5 W level. In the used gradient-index fiber, the output beam has 4.5 lower divergence as compared with the pump beam thus demonstrating a new way for development of high-power fiber lasers with high-quality output.
Collapse
Affiliation(s)
- S A Babin
- Institute of Automation and Electrometry, SB RAS, Novosibirsk 630090, Russia.
| | | | | |
Collapse
|
31
|
Ballato J, Hawkins T, Foy P, Stolen R, Kokuoz B, Ellison M, McMillen C, Reppert J, Rao AM, Daw M, Sharma SR, Shori R, Stafsudd O, Rice RR, Powers DR. Silicon optical fiber. OPTICS EXPRESS 2008; 16:18675-18683. [PMID: 19581953 DOI: 10.1364/oe.16.018675] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Described herein are initial experimental details and properties of a silicon core, silica glass-clad optical fiber fabricated using conventional optical fiber draw methods. Such semiconductor core fibers have potential to greatly influence the fields of nonlinear fiber optics, infrared and THz power delivery. More specifically, x-ray diffraction and Raman spectroscopy showed the core to be highly crystalline silicon. The measured propagation losses were 4.3 dB/m at 2.936 microm, which likely are caused by either microcracks in the core arising from the large thermal expansion mismatch with the cladding or to SiO(2) precipitates formed from oxygen dissolved in the silicon melt. Suggestions for enhancing the performance of these semiconductor core fibers are provided. Here we show that lengths of an optical fiber containing a highly crystalline semiconducting core can be produced using scalable fiber fabrication techniques.
Collapse
Affiliation(s)
- J Ballato
- Center for Optical Materials Science and Engineering Technologies (COMSET), School of Materials Science and Engineering, Clemson University, Clemson, SC 29634 USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Zhu X, Schülzgen A, Li H, Li L, Wang Q, Suzuki S, Temyanko VL, Moloney JV, Peyghambarian N. Single-transverse-mode output from a fiber laser based on multimode interference. OPTICS LETTERS 2008; 33:908-910. [PMID: 18451935 DOI: 10.1364/ol.33.000908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
An alternative original approach to achieve single-transverse-mode laser emissions from multimode (MM) active fibers is demonstrated. The fiber cavity is constructed by simply splicing a conventional passive single-mode fiber (SMF-28) onto a few centimeters-long active MM fiber section whose length is precisely controlled. Owing to the self-imaging property of multimode interference (MMI) in the MM fiber, diffraction-limited laser output is obtained from the end of the SMF-28, and the MMI fiber laser is nearly as efficient as the corresponding MM fiber laser. Moreover, because of the spectral filtering effect during in-phase MMI, the bandwidth of the MMI fiber laser is below 0.5 nm.
Collapse
Affiliation(s)
- X Zhu
- College of Optical Sciences, University of Arizona, 1630 East University Boulevard, Tucson, Arizona 85721, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Terry NB, Alley TG, Russell TH. An explanation of SRS beam cleanup in graded-index fibers and the absence of SRS beam cleanup in step-index fibers. OPTICS EXPRESS 2007; 15:17509-17519. [PMID: 19551044 DOI: 10.1364/oe.15.017509] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Beam cleanup via stimulated Raman scattering in multimode fibers is modeled by numerically considering the competition between the Stokes modes of graded-index and step-index fibers. The relative gain of each Stokes mode is calculated by considering the overlap the various pump and Stokes modes of the fibers. Mode competition in a graded-index fiber favors the LP(01) Stokes mode while mode competition in a step-index fiber does not favor the LP(01) Stokes mode. This model explains why beam cleanup has only been reported for graded-index fibers and not for step-index fibers.
Collapse
Affiliation(s)
- Nathan B Terry
- Air Force Institute of Technology, 2950 Hobson Way, Wright-Patterson Air Force Base, OH 454332, USA.
| | | | | |
Collapse
|
34
|
Terry NB, Engel KT, Alley TG, Russell TH. Use of a continuous wave Raman fiber laser in graded-index multimode fiber for SRS beam combination. OPTICS EXPRESS 2007; 15:602-607. [PMID: 19532281 DOI: 10.1364/oe.15.000602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We report using a Raman fiber laser (RFL) based on a multimode graded-index fiber as a novel method for beam combination of two continuous wave pump beams. Due to stimulated Raman scattering, the RFL generates a Stokes beam which can be up to 300% brighter than the pump beams. Up to 5.8 W of Stokes power is generated with an optical conversion efficiency of 56%.
Collapse
|
35
|
Codemard CA, Dupriez P, Jeong Y, Sahu JK, Ibsen M, Nilsson J. High-power continuous-wave cladding-pumped Raman fiber laser. OPTICS LETTERS 2006; 31:2290-2. [PMID: 16832462 DOI: 10.1364/ol.31.002290] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We demonstrate a high-power single-mode cladding-pumped Raman fiber laser. The Raman fiber laser consists of a 1.2 km long germanium-doped double-clad fiber in a linear cavity, which is spliced to a single-mode fiber. The laser is end pumped by a multimode erbium-ytterbium-doped fiber, which is coupled to the inner cladding of the Raman fiber. The embedded core was designed to be single mode at the Raman Stokes wavelength, and up to 10 W of power was obtained at 1660 nm from the single-mode fiber end. The laser has a slope efficiency of 67% and a threshold of 6.5 W.
Collapse
Affiliation(s)
- C A Codemard
- Optoelectronics Research Centre, University of Southampton, SO 17 1BJ, England
| | | | | | | | | | | |
Collapse
|