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Liu D, Mao X, Bi G, Li T, Zang D, Sun N. Efficiency Enhancing Technique for Rod Fiber Picosecond Amplifiers with Optimal Mode Field Matching. MICROMACHINES 2023; 14:450. [PMID: 36838150 PMCID: PMC9959118 DOI: 10.3390/mi14020450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 02/08/2023] [Accepted: 02/09/2023] [Indexed: 06/18/2023]
Abstract
A high power and high quality picosecond laser is crucial in MEMS fabrication regarding micromachines. Optimal seed beam coupling is an important precondition to enhance laser efficiency. However, empirical coupling limits its development. In this paper, the physical parameters related to coupling are determined. The relationships among them are established under optical mode matching constraints to satisfy optimal seed beam coupling. According to a theoretical analysis, the focal length cut-off and the optimal coupling position of the coupling lens are acquired. A maximum transmittance of 87.2% is acquired with a 6 W input seed power in the validation experiment. In further power amplification experiments, a diffraction-limited beam quality is achieved, with M2X = 1.111, M2Y = 1.017, an optical efficiency of 60.5% and a slope efficiency of 66%, benefiting from the previous theoretical guidance.
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Affiliation(s)
- Danni Liu
- Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiaojie Mao
- Science and Technology on Solid-State Laser Laboratory, North China Research Institute of Electro-Optics, Beijing 100015, China
| | - Guojiang Bi
- Science and Technology on Solid-State Laser Laboratory, North China Research Institute of Electro-Optics, Beijing 100015, China
| | - Tianqi Li
- The Science and Technology on Inertial Laboratory, School of Instrumentation and Opto-Electronics Engineering, Beihang University, Beijing 100191, China
| | - Dawei Zang
- Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100190, China
| | - Ninghui Sun
- Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100190, China
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2
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Koshiba Y, Otsuka S, Yamashita K, Fukushima C, Araki S, Aryshev A, Omori T, Popov K, Takahashi T, Terunuma N, Uesugi Y, Urakawa J, Washio M. Harmonically mode-locked laser pulse accumulation in a self-resonating optical cavity. OPTICS EXPRESS 2022; 30:43888-43899. [PMID: 36523077 DOI: 10.1364/oe.472917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 11/05/2022] [Indexed: 06/17/2023]
Abstract
Optical enhancement cavities enabling laser pulses to be coherently stacked in free space are used in several applications to enhance accessible optical power. In this study, we develop an optical cavity that accumulates harmonically mode-locked laser pulses with a self-resonating mechanism for X-ray sources based on laser-Compton scattering. In particular, a Fabry-Perot cavity composed of 99% reflectance mirrors maintained the optical resonance in a feedback-free fashion for more than half an hour and automatically resumed the accumulation even if the laser oscillation was suspended. In contrast to conventional optical enhancement cavity systems with a dedicated feedback controller, this characteristic is highly beneficial in practical applications, such as for laser-Compton scattering X-ray sources. Lastly, upscaling and adoption of the proposed system might improve the operability and equipment use of laser Compton-scattering X-ray sources.
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3
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Synthesis of Carbon Nanodots from Sugarcane Syrup, and Their Incorporation into a Hydrogel-Based Composite to Fabricate Innovative Fluorescent Microstructured Polymer Optical Fibers. Gels 2022; 8:gels8090553. [PMID: 36135265 PMCID: PMC9498784 DOI: 10.3390/gels8090553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 08/28/2022] [Accepted: 08/29/2022] [Indexed: 12/05/2022] Open
Abstract
Carbon nanodots (CNDs) are interesting materials due to their intrinsic fluorescence, electron-transfer properties, and low toxicity. Here, we report a sustainable, cheap, and scalable methodology to obtain CNDs from sugarcane syrup using a domestic microwave oven. The CNDs were characterized by infrared spectroscopy, dynamic light scattering, atomic force microscopy, absorption, and emission spectroscopies. The CNDs have 3 nm in diameter with low polydispersity and are fluorescent. A fluorescent hydrogel–CNDs composite was obtained using gelatin polypeptide as the polymeric matrix. The new hydrogel–CNDs composite was incorporated in the cavities of a double-clad optical fiber using an innovative approach that resulted in a microstructured polymer optical fiber with intrinsic fluorescence. This work shows a promising alternative for the fabrication of fluorescent materials since the CNDs synthesis is sustainable and environmentally friendly. These CNDs might substitute the rare-earth and other heavy metals of high cost and toxicity, which are usually incorporated in double-clad fibers for applications on lasers, amplifiers, and spectroscopy.
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4
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Advances in Silica-Based Large Mode Area and Polarization-Maintaining Photonic Crystal Fiber Research. MATERIALS 2022; 15:ma15041558. [PMID: 35208097 PMCID: PMC8878035 DOI: 10.3390/ma15041558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/13/2022] [Accepted: 02/16/2022] [Indexed: 12/10/2022]
Abstract
In recent years, photonic crystal fibers (PCFs) have attracted increasing attention. Compared with traditional optical fibers, PCFs exhibit many unique optical properties and superior performance due to their high degree of structural design freedom. Using large-mode area (LMA) fibers with single-mode operation is essential to overcoming emerging problems as the power of fiber lasers scales up, which can effectively reduce the power density and mitigate the influence of nonlinear effects. With a brief introduction of the concept, classification, light transmission mechanism, basic properties, and theoretical analysis methods of PCFs, this paper mainly compiles the worldwide development of large-mode area and polarization-maintaining (PM) PCFs, and finally proposes possible technical routes to realize the single-mode operation of LMA-PCFs and PM-LMA-PCFs. Finally, the future development prospects of the PCFs are discussed.
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5
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Khan MRH, Ali FAM, Islam MR. THz sensing of CoViD-19 disinfecting products using photonic crystal fiber. SENSING AND BIO-SENSING RESEARCH 2021. [DOI: 10.1016/j.sbsr.2021.100447] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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6
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Zhang Y, Wang J, Teng H, Fang S, Wang J, Chang G, Wei Z. Double-pass pre-chirp managed amplification with high gain and high average power. OPTICS LETTERS 2021; 46:3115-3118. [PMID: 34197394 DOI: 10.1364/ol.428066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 06/02/2021] [Indexed: 06/13/2023]
Abstract
We demonstrate, to the best of our knowledge, the first double-pass pre-chirp managed fiber amplifier. The double-pass fiber amplifier exhibits high gain allowing us to amplify chirped picosecond pulses from 20 mW to 113 W in a rod-type Yb-fiber corresponding to 38 dB gain. We study the dependence of static mode degradation (SMD) on the nonlinear phase shift (NPS) accumulated by the amplified pulse. Our results indicate that a larger nonlinear phase shift results in stronger nonlinear polarization evolution of the fundamental mode and leads to a lower threshold for SMD. After optimization, our pre-chirp managed amplifier seeded by 80 mW pulses delivers 102 W amplified power from the main output. The amplified pulses are compressed to 37 (55) fs with 90 (100) W average power by a grating pair (chirped mirrors). The double-pass configuration significantly simplifies the implementation of pre-chirp managed fiber amplifiers leading to an extremely compact system.
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7
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Veinhard M, Bellanger S, Daniault L, Fsaifes I, Bourderionnet J, Larat C, Lallier E, Brignon A, Chanteloup JC. Orbital angular momentum beams generation from 61 channels coherent beam combining femtosecond digital laser. OPTICS LETTERS 2021; 46:25-28. [PMID: 33362004 DOI: 10.1364/ol.405975] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 11/21/2020] [Indexed: 06/12/2023]
Abstract
We report on the use of a 61 beamlets coherent beam combination femtosecond fiber amplifiers as a digital laser source to generate high-power orbital angular momentum beams. Such an approach opens the path for higher-order non-symmetrical user-defined far field distributions.
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Sidharthan R, Lin D, Jie Lim K, Li H, Huiting Lim S, Jian Chang C, Men Seng Y, Liang Chua S, Jung Y, Richardson DJ, Yoo S. Ultra-low NA step-index large mode area Yb-doped fiber with a germanium doped cladding for high power pulse amplification. OPTICS LETTERS 2020; 45:3828-3831. [PMID: 32667295 DOI: 10.1364/ol.396157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 05/28/2020] [Indexed: 06/11/2023]
Abstract
High concentration rare earth doped, large mode area (LMA) step-index fibers, which feature a very high cladding absorption per unit length at the pump wavelength, high efficiency, and excellent beam quality, are ideal for high power pulsed fiber lasers/amplifiers where large effective mode areas and short device lengths are crucial in order to reduce detrimental nonlinear effects associated with high peak power operation. In this Letter, we realize low numerical aperture (NA) high absorption fibers, simply by employing a germanium (Ge)-doped cladding rather than a pure silica cladding to offset the high refractive index associated with using a high concentration of ytterbium (Yb) in the core. This approach allows us to separate the two inter-linked fiber design parameters of pump absorption and NA in a step-index fiber. Using a conventional modified chemical vapor deposition process combined with solution doping, a low NA (0.04), LMA (475µm2) silica fiber is fabricated with a cladding absorption value of >20dB/m, which is the highest value among LMA step-index fibers with NA<0.06 so far reported to the best of our knowledge. The fabricated Yb-doped fiber was tested in a high-power picosecond amplifier system and enabled the generation of 190 ps laser pulses with a 101 µJ pulse energy and 0.5 MW peak power at an average power of 150 W.
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9
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Chang G, Wei Z. Ultrafast Fiber Lasers: An Expanding Versatile Toolbox. iScience 2020; 23:101101. [PMID: 32408170 PMCID: PMC7225726 DOI: 10.1016/j.isci.2020.101101] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 04/14/2020] [Accepted: 04/21/2020] [Indexed: 11/02/2022] Open
Abstract
Ultrafast fiber lasers have gained rapid advances in last decades for their intrinsic merits such as potential of all-fiber format, excellent beam quality, superior power scalability, and high single-pass gain, which opened widespread applications in high-field science, laser machining, precision metrology, optical communication, microscopy and spectroscopy, and modern ophthalmology, to name a few. Performance of an ultrafast fiber laser is well defined by the laser parameters including repetition rate, spectral bandwidth, pulse duration, pulse energy, wavelength tuning range, and average power. During past years, these parameters have been pushed to an unprecedented level. In this paper, we review these enabling technologies and explicitly show that the nonlinear interaction between ultrafast pulses and optical fibers plays the essential role. As a result of rapid development in both active and passive fibers, the toolbox of ultrafast fiber lasers will continue to expand and provide solutions to scientific and industrial problems.
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Affiliation(s)
- Guoqing Chang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China.
| | - Zhiyi Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China; Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China.
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10
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Ahmad R, Abedin KS, Yan MF, Nicholson JW, Westbrook PS, DiGiovanni DJ. Polarization-maintained propagation of a 2200 μm 2 effective-area higher-order-mode in a bent optical fiber. OPTICS EXPRESS 2020; 28:8400-8406. [PMID: 32225466 DOI: 10.1364/oe.382165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 02/12/2020] [Indexed: 06/10/2023]
Abstract
We report on the excitation and polarization preserved propagation of a very large effective-area (Aeff ∼ 2240 μm2) higher-order-mode in an optical fiber. A laser signal operating in the 1 μm wavelength region is transported in a Bessel-like LP0,4 mode over a 10 m long section of the polarization-maintaining higher-order-mode fiber. We observe that the light propagates through the fiber with >10 dB polarization-extinction-ratio as the fiber is coiled into circular loops of 40 cm diameter.
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11
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Franczyk M, Pysz D, Pucko P, Michalik D, Biduś M, Dłubek M, Buczyński R. Yb 3+ doped silica nanostructured core fiber laser. OPTICS EXPRESS 2019; 27:35108-35119. [PMID: 31878686 DOI: 10.1364/oe.27.035108] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 11/05/2019] [Indexed: 06/10/2023]
Abstract
We report development of ytterbium doped silica fiber with nanostructured core for laser applications. We study influence of non-continuous distributed Yb dopants on gain, beam quality, and fiber laser performance. The fiber core is composed of over 43 thousand nanorods with a central part doped with Yb. The diameter of each nanorod is 72 nm. With this method we obtained a flat refractive index profile with uniformity of 1.3 × 10-4 refractive index unit (RIU) despite the non-uniformity of 1.2 × 10-3 RIU in Yb doped preform rods used for the fiber development. We demonstrate a nanostructured core single-mode fiber laser with 61.8% of slope efficiency, and extremely low numerical aperture 0.027 of generated mode.
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12
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Fedotov A, Noronen T, Gumenyuk R, Ustimchik V, Chamorovskii Y, Golant K, Odnoblyudov M, Rissanen J, Niemi T, Filippov V. Ultra-large core birefringent Yb-doped tapered double clad fiber for high power amplifiers. OPTICS EXPRESS 2018; 26:6581-6592. [PMID: 29609346 DOI: 10.1364/oe.26.006581] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 02/25/2018] [Indexed: 06/08/2023]
Abstract
We present a birefringent Yb-doped tapered double-clad fiber with a record core diameter of 96 µm. An impressive gain of over 38 dB was demonstrated for linearly polarized CW and pulsed sources at a wavelength of 1040 nm. For the CW regime the output power was70 W. For a mode-locked fiber laser a pulse energy of 28 µJ with 292 kW peak power was reached at an average output power of 28 W for a 1 MHz repetition rate. The tapered double-clad fiber has a high value of polarization extinction ratio at 30 dB and is capable of delivering the linearly polarized diffraction-limited beam (M2 = 1.09).
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13
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Sanjabi Eznaveh Z, Antonio-Lopez JE, Anderson J, Schülzgen A, Amezcua-Correa R. Reduced-symmetry LMA rod-type fiber for enhanced higher-order mode delocalization. OPTICS LETTERS 2017; 42:1974-1977. [PMID: 28504727 DOI: 10.1364/ol.42.001974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We present a novel design of a micro-structured large-pitch, large-mode-area (LMA) asymmetric rod-type fiber. By reducing the cladding symmetry through six high-refractive index germanium-doped silica inclusions, the fiber features strong higher-order mode (HOM) delocalization, leading to a potentially enhanced preferential gain for the fundamental mode in active fibers. In addition, high resolution spatially and spectrally (S2) resolved mode analysis measurements confirm HOM contributions below 1% and LP1m-like HOM contributions below the detection limit. This proposed fiber design enables single-mode operation, with near-diffraction-limited beam quality of M2=1.3 and an effective mode area of 2560 μm2 at 1064 nm. This design opens new insights into improving the threshold-like onset of modal instabilities in high-power fiber lasers and fiber amplifiers by efficiently suppressing LP11 modes.
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14
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Nicholson JW, DeSantolo A, Westbrook PS, Windeler RS, Kremp T, Headley C, DiGiovanni DJ. Axicons for mode conversion in high peak power, higher-order mode, fiber amplifiers. OPTICS EXPRESS 2015; 23:33849-33860. [PMID: 26832045 DOI: 10.1364/oe.23.033849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Higher-order mode fiber amplifiers have demonstrated effective areas as large as 6000 μm2, allowing for high pulse energy and peak power amplification. Long-period gratings are used to convert the fundamental mode to the higher-order mode at the entrance to the amplifier, and reconvert back to the fundamental at the exit, to achieve a diffraction limited beam. However, long period gratings are susceptible to nonlinearity at high peak power. In this work, we propose and demonstrate axicons for linear bulk-optic mode conversion at the output of higher order mode amplifiers. We achieve an M2 of less than 1.25 for 80% mode conversion efficiency. Experiments with pulsed amplifiers confirm that the mode conversion is free from nonlinearity. Furthermore, chirp pulse amplifier experiments confirm that HOM amplifiers plus axicon mode convertors provide energy scalability in femtosecond pulses, compared to smaller effective area, fundamental mode fiber amplifiers. We also propose and demonstrate a route towards fiber integration of the axicon mode convertor by fabricating axicons directly on the tip of the fiber amplifier end-cap.
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15
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Zhao N, Xing YB, Li JM, Liao L, Wang YB, Peng JG, Yang LY, Dai NL, Li HQ, Li JY. 793 nm pump induced photo-bleaching of photo-darkened Yb(3+)-doped fibers. OPTICS EXPRESS 2015; 23:25272-25278. [PMID: 26406724 DOI: 10.1364/oe.23.025272] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report on the strong photo-bleaching of the photo-darkening (PD) induced loss under the cladding pump of a 793 nm laser diode (LD) in double clad Yb-doped fibers. Up to 68% PD loss at 810 nm was bleached. The bleaching rates under different powers show that the higher pump power corresponds to the more bleached loss within the same time. Moreover, repeatable processes of PD and photo-bleaching were observed when alternately pumped with 915 and 793 nm LDs. Furthermore, it was found that simultaneously pumping the fiber with 915 and 793 nm LDs can suppress about 80% PD loss, compared with pumping the fiber only with 915 nm LD. The mechanism of photo-bleaching under 793 nm pump was also discussed.
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16
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Stępień R, Franczyk M, Pysz D, Kujawa I, Klimczak M, Buczyński R. Ytterbium-Phosphate Glass for Microstructured Fiber Laser. MATERIALS 2014; 7:4723-4738. [PMID: 28788702 PMCID: PMC5455909 DOI: 10.3390/ma7064723] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 06/11/2014] [Accepted: 06/11/2014] [Indexed: 11/30/2022]
Abstract
In the paper, we report on the development of a synthesis and melting method of phosphate glasses designed for active microstructured fiber manufacturing. Non-doped glass synthesized in a P2O5-Al2O3-BaO-ZnO-MgO-Na2O oxide system served as the matrix material; meanwhile, the glass was doped with 6 mol% (18 wt%) of Yb2O3, as fiber core. The glasses were well-fitted in relation to optical (refractive index) and thermal proprieties (thermal expansion coefficient, rheology). The fiber with the Yb3+-doped core, with a wide internal photonic microstructure for a laser pump, as well as with a high relative hole size in the photonic outer air-cladding, was produced. The laser built on the basis of this fiber enabled achieving 8.07 W of output power with 20.5% slope efficiency against the launched pump power, in single-mode operation M2 = 1.59, from a 53 cm-long cavity.
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Affiliation(s)
- Ryszard Stępień
- Institute of Electronic Materials Technology, 133 Wolczynska Str., 01-919 Warsaw, Poland.
| | - Marcin Franczyk
- Institute of Electronic Materials Technology, 133 Wolczynska Str., 01-919 Warsaw, Poland.
| | - Dariusz Pysz
- Institute of Electronic Materials Technology, 133 Wolczynska Str., 01-919 Warsaw, Poland.
| | - Ireneusz Kujawa
- Institute of Electronic Materials Technology, 133 Wolczynska Str., 01-919 Warsaw, Poland.
| | - Mariusz Klimczak
- Institute of Electronic Materials Technology, 133 Wolczynska Str., 01-919 Warsaw, Poland.
| | - Ryszard Buczyński
- Institute of Electronic Materials Technology, 133 Wolczynska Str., 01-919 Warsaw, Poland.
- Department of Physics, University of Warsaw, 7 Pasteura Str., 02-093 Warsaw, Poland.
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17
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Dasgupta S, Hayes JR, Richardson DJ. Leakage channel fibers with microstuctured cladding elements: a unique LMA platform. OPTICS EXPRESS 2014; 22:8574-8584. [PMID: 24718229 DOI: 10.1364/oe.22.008574] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present a novel design of leakage channel fiber (LCF) that incorporates an air-hole lattice to define the modal filtering characteristics. The approach has the potential to offer single-mode, large mode area (LMA) fibers in a single-material platform with bend loss characteristics comparable to all-solid (LCFs) whilst at the same time providing significant fabrication benefits. We compare the performance of the proposed fiber with that of rod-type photonic crystal fibers (PCFs) and all-solid LCFs offering a similar effective mode area of ~1600μm(2) at 1.05μm. Our calculations show that the proposed fiber concept succeeds in combining the advantages of the use of small air holes and the larger design space of rod-type PCFs with the improved bend tolerance and greater higher order mode discrimination of all-solid LCFs, while alleviating their respective issues of rigidity and restricted material design space. We report the fabrication and experimental characterization of a first exemplar fiber, which we demonstrate offers a single-mode output with a fundamental mode area ~1440µm(2) at 1.06µm, and that can be bent down to a radius of 20cm with a bend loss of <3dB/turn. Finally we show that the proposed design concept can be adopted to achieve larger mode areas (> 3000µm(2)), albeit at the expense of reduced bend tolerance.
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18
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Peng X, Kim K, Mielke M, Booth T, Nicholson JW, Fini JM, Liu X, Desantolo A, Westbrook PS, Windeler RS, Monberg EM, Dimarcello FV, Headley C, Digiovanni DJ. Higher-order mode fiber enables high energy chirped-pulse amplification. OPTICS EXPRESS 2013; 21:32411-32416. [PMID: 24514834 DOI: 10.1364/oe.21.032411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Energy scaling of femtosecond fiber lasers has been constrained by nonlinear impairments and optical fiber damage. Reducing the optical irradiance inside the fiber by increasing mode size lowers these effects. Using an erbium-doped higher-order mode fiber with 6000 µm(2) effective area and output fundamental mode re-conversion, we show a breakthrough in pulse energy from a monolithic fiber chirped pulse amplification system using higher-order mode propagation generating 300 µJ pulses with duration <500 fs (FWHM) and peak power >600 MW at 1.55 µm. The erbium-doped HOM fiber has both a record large effective mode area and excellent mode stability, even when coiled to reasonable diameter. This demonstration proves efficacy of a new path for high energy monolithic fiber-optic femtosecond laser systems.
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19
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Wan P, Yang LM, Liu J. All fiber-based Yb-doped high energy, high power femtosecond fiber lasers. OPTICS EXPRESS 2013; 21:29854-29859. [PMID: 24514535 DOI: 10.1364/oe.21.029854] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Two all fiber-based laser systems are demonstrated to achieve high energy and high average power femtosecond pulsed outputs at wavelength of 1 µm. In the high energy laser system, a pulse energy of 1.05 mJ (0.85 mJ after pulse compressor) at 100 kHz repetition rate has been realized by a Yb-doped ultra large-core single-mode photonic crystal fiber (PCF) rod amplifier, seeded with a 50 µJ fiber laser. The pulse duration is 705 fs. In the high average power experiment, a large mode area (LMA) fiber has been used in the final stage amplifier, seeded with a 50 W mode locked fiber laser. The system is running at a repetition rate of 69 MHz producing 1052 W of average power before compressor. After pulse compression, a pulse duration of 800 fs was measured.
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20
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Jain D, Baskiotis C, Sahu JK. Bending performance of large mode area multi-trench fibers. OPTICS EXPRESS 2013; 21:26663-26670. [PMID: 24216887 DOI: 10.1364/oe.21.026663] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Bending performance of the Multi-trench Fibers (MTFs) has been investigated using the Finite Element Method. Numerical investigations show that MTFs can provide low-loss effective single mode operation under bent configuration, thanks to the resonant coupling of the Higher order Modes (HOMs). Large ratio between the HOMs and the Fundamental Mode (FM) losses can be ensured, although the ratio drops with increasing Effective Area (A(eff)) of the FM. MTFs provide better losses ratio between the HOMs and the FM in comparison with other fibers like step-index, W-type, and parabolic fibers.
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21
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Li L, Zhang A, Zhan H, He J, Shi T, Zhou Z, Xiao X, Lin A. Multiring large-mode-area delivery fiber for high power. APPLIED OPTICS 2013; 52:7407-7410. [PMID: 24216638 DOI: 10.1364/ao.52.007407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 09/25/2013] [Indexed: 06/02/2023]
Abstract
The study presents a novel design of multiring delivery fiber with large mode area for high power. Using a FiberCAD method, we investigated a fiber whose core is surrounded by alternative low- and high-index rings. Based on our calculation, the effective area is 400 μm2 at 1.08 μm, larger than the ~280 μm2 of conventional step-index fiber (20/400). The macrobending loss at 1.08 μm is estimated to be 1×10(-3) dB/m, approximately one-third that of conventional step-index fiber (20/400). The single-mode operation can be achieved by the macrobending loss contrast between the fundamental mode (<1 dB/m) and high-order mode (>100 dB/m). The results indicate that multiring delivery fiber fabricated by modified chemical vapor deposition process is a promising candidate for high-power transmission.
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Peng X, Kim K, Mielke M, Jennings S, Masor G, Stohl D, Chavez-Pirson A, Nguyen DT, Rhonehouse D, Zong J, Churin D, Peyghambarian N. High efficiency, monolithic fiber chirped pulse amplification system for high energy femtosecond pulse generation. OPTICS EXPRESS 2013; 21:25440-25451. [PMID: 24150384 DOI: 10.1364/oe.21.025440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A novel monolithic fiber-optic chirped pulse amplification (CPA) system for high energy, femtosecond pulse generation is proposed and experimentally demonstrated. By employing a high gain amplifier comprising merely 20 cm of high efficiency media (HEM) gain fiber, an optimal balance of output pulse energy, optical efficiency, and B-integral is achieved. The HEM amplifier is fabricated from erbium-doped phosphate glass fiber and yields gain of 1.443 dB/cm with slope efficiency >45%. We experimentally demonstrate near diffraction-limited beam quality and near transform-limited femtosecond pulse quality at 1.55 µm wavelength. With pulse energy >100 µJ and pulse duration of 636 fs (FWHM), the peak power is estimated to be ~160 MW. NAVAIR Public Release Distribution Statement A-"Approved for Public release; distribution is unlimited".
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23
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Valentin C, Calvet P, Quiquempois Y, Bouwmans G, Bigot L, Coulombier Q, Douay M, Delplace K, Mussot A, Hugonnot E. Top-hat beam output of a single-mode microstructured optical fiber: impact of core index depression. OPTICS EXPRESS 2013; 21:23250-23260. [PMID: 24104239 DOI: 10.1364/oe.21.023250] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A new strategy to obtain a single-mode fiber with a flattened intensity profile distribution is presented. It is based on the use of an OVD-made high index ring deposited on a silica rod having a refractive index slightly lower than the silica used for the microstructured cladding. Using this strategy, we realized the first single-mode fiber with a quasi-perfect top-hat intensity profile around 1 µm. Numerical studies clearly demonstrate the advantage of using a core index depression to insure the single-mode operation of the fiber at the working wavelength.
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24
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Horton NG, Wang K, Kobat D, Clark CG, Wise FW, Schaffer CB, Xu C. In vivo three-photon microscopy of subcortical structures within an intact mouse brain. NATURE PHOTONICS 2013; 7:205-209. [PMID: 24353743 PMCID: PMC3864872 DOI: 10.1038/nphoton.2012.336] [Citation(s) in RCA: 704] [Impact Index Per Article: 64.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Two-photon fluorescence microscopy (2PM)1 enables scientists in various fields including neuroscience2,3, embryology4, and oncology5 to visualize in vivo and ex vivo tissue morphology and physiology at a cellular level deep within scattering tissue. However, tissue scattering limits the maximum imaging depth of 2PM within the mouse brain to the cortical layer, and imaging subcortical structures currently requires the removal of overlying brain tissue3 or the insertion of optical probes6,7. Here we demonstrate non-invasive, high resolution, in vivo imaging of subcortical structures within an intact mouse brain using three-photon fluorescence microscopy (3PM) at a spectral excitation window of 1,700 nm. Vascular structures as well as red fluorescent protein (RFP)-labeled neurons within the mouse hippocampus are imaged. The combination of the long excitation wavelength and the higher order nonlinear excitation overcomes the limitations of 2PM, enabling biological investigations to take place at greater depth within tissue.
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Affiliation(s)
- Nicholas G Horton
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - Ke Wang
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - Demirhan Kobat
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - Catharine G Clark
- Department of Biomedical Engineering, Cornell University, Ithaca, New York, 14853, USA
| | - Frank W Wise
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - Chris B Schaffer
- Department of Biomedical Engineering, Cornell University, Ithaca, New York, 14853, USA
| | - Chris Xu
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
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25
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Jain D, Baskiotis C, Sahu JK. Mode area scaling with multi-trench rod-type fibers. OPTICS EXPRESS 2013; 21:1448-1455. [PMID: 23389126 DOI: 10.1364/oe.21.001448] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We propose a novel all-solid rod-type fiber structure that presents a cylindrical symmetry and low refractive-index contrasts. Effectively single-mode propagation for the fundamental mode is ensured thanks to resonant couplings between Higher Order Modes (HOMs) and cladding modes. Numerical simulations demonstrate the possibility of achieving a fundamental mode effective area as large as 5000 µm² at a wavelength of 1.06 μm in fibers ensuring a high leakage loss ratio (>100) between the HOMs and the fundamental mode while keeping the fundamental mode leakage losses at a level lower than 0.2dB/m. Further scaling to an effective area of 12,200 µm2 at 1.06 μm in an effectively single-mode fiber is also presented by exploiting the power delocalization of several HOMs on top of the high-leakage loss filtering.
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Affiliation(s)
- Deepak Jain
- Optoelectronics Research Center, University of Southampton, Southampton SO17 1BJ, UK.
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26
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Marciante JR, Shkunov VV, Rockwell DA. Semi-guiding high-aspect-ratio core (SHARC) fiber amplifiers with ultra-large core area for single-mode kW operation in a compact coilable package. OPTICS EXPRESS 2012; 20:20238-20254. [PMID: 23037076 DOI: 10.1364/oe.20.020238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A new class of optical fiber, the SHARC fiber, is analyzed in a high-power fiber amplifier geometry using the gain-filtering properties of confined-gain dopants. The high-aspect-ratio (~30:1) rectangular core allows mode-area scaling well beyond 10,000 μm2, which is critical to high-pulse-energy or narrow-linewidth high-power fiber amplifiers. While SHARC fibers offer modally dependent edge loss at the wide "semi-guiding" edge of the waveguide, the inclusion of gain filtering adds further modal discrimination arising from the variation of the spatial overlap of the gain with the various modes. Both methods are geometric in form, such that the combination provides nearly unlimited scalability in mode area. Simulations show that for kW-class fiber amplifiers, only the fundamental mode experiences net gain (15 dB), resulting in outstanding beam quality. Further, misalignment of the seed beam due to offset, magnification, and tilt are shown to result in a small (few percent) efficiency penalty while maintaining kW-level output with 99% of the power in the fundamental mode for all cases.
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Affiliation(s)
- John R Marciante
- University of Rochester, Institute of Optics, 275 Hutchison Rd, Rochester, NY 14627, USA.
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27
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Petkovšek R, Saby J, Salin F, Schumi T, Bammer F. SCPEM-Q-switching of a fiber-rod-laser. OPTICS EXPRESS 2012; 20:7415-7421. [PMID: 22453421 DOI: 10.1364/oe.20.007415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We demonstrate high-frequency Q-switching of a fiber rod laser with a Single-Crystal Photo-Elastic Modulator (SCPEM) made of a LiTaO₃₋ crystal. This type of photo-elastic modulator can be driven simultaneously with two different eigenmodes to achieve a shorter rise time, which is essential for high-power operation. When operated in the laser cavity, a pulse repetition frequency of 183.6 kHz with an average power of 47 W, a pulse duration of 26 ns, and a peak power of 10.5 kW was achieved.
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Affiliation(s)
- Rok Petkovšek
- University of Ljubljana, Faculty of Mechanical Engineering, Aškerčeva 6, SI-1000 Ljubljana, Slovenia.
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28
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Koyama M, Hirose T, Okida M, Miyamoto K, Omatsu T. Nanosecond vortex laser pulses with millijoule pulse energies from a Yb-doped double-clad fiber power amplifier. OPTICS EXPRESS 2011; 19:14420-14425. [PMID: 21934804 DOI: 10.1364/oe.19.014420] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Nanosecond vortex pulses were generated using a stressed, large-mode-area, Yb-doped, fiber amplifier with an off-axis coupling technique for the first time. A pulse energy of 0.83 mJ (corresponding to a peak power of 59 kW) was achieved at a pump power of 25.7 W. The optical-optical efficiency was measured to be 31%. The millijoule nanosecond vortex pulses will be potentially applied to novel material processing, such as metal microneedle fabrication.
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Affiliation(s)
- Mio Koyama
- Graduate School of Advanced Integration Science, Chiba University,1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
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29
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Rockwell DA, Shkunov VV, Marciante JR. Semi-guiding high-aspect-ratio core (SHARC) fiber providing single-mode operation and an ultra-large core area in a compact coilable package. OPTICS EXPRESS 2011; 19:14746-14762. [PMID: 21934837 DOI: 10.1364/oe.19.014746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A new class of optical fiber is presented that departs from the circular-core symmetry common to conventional fibers. By using a high-aspect-ratio (~30:1) rectangular core, the mode area can be significantly expanded well beyond 10,000 μm2. Moreover, by also specifying a very small refractive-index step at the narrow core edges, the core becomes "semi-guiding," i.e. it guides in the narrow dimension and is effectively un-guiding in the wide mm-scale dimension. The mode dependence of the resulting Fresnel leakage loss in the wide dimension strongly favors the fundamental mode, promoting single-mode operation. Since the modal loss ratios are independent of mode area, this core structure offers nearly unlimited scalability. The implications of using such a fiber in fiber laser and amplifier systems are also discussed.
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Affiliation(s)
- David A Rockwell
- Raytheon Space and Airborne Systems, 2000 East El Segundo Boulevard, PO Box 902 El Segundo, California 90245, USA
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30
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Laurila M, Saby J, Alkeskjold TT, Scolari L, Cocquelin B, Salin F, Broeng J, Lægsgaard J. Q-switching and efficient harmonic generation from a single-mode LMA photonic bandgap rod fiber laser. OPTICS EXPRESS 2011; 19:10824-10833. [PMID: 21643339 DOI: 10.1364/oe.19.010824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We demonstrate a Single-Mode (SM) Large-Mode-Area (LMA) ytterbium-doped PCF rod fiber laser with stable and close to diffraction limited beam quality with 110W output power. Distributed-Mode-Filtering (DMF) elements integrated in the cladding of the rod fiber provide a robust spatial mode with a Mode-Field-Diameter (MFD) of 59μm. We further demonstrate high pulse energy Second-Harmonic-Generation (SHG) and Third Harmonic Generation (THG) using a simple Q-switched single-stage rod fiber laser cavity architecture reaching pulse energies up to 1mJ at 515nm and 0.5mJ at 343nm.
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Affiliation(s)
- Marko Laurila
- DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, 2800 Kgs Lyngby, Denmark.
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31
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Jauregui C, Eidam T, Limpert J, Tünnermann A. The impact of modal interference on the beam quality of high-power fiber amplifiers. OPTICS EXPRESS 2011; 19:3258-71. [PMID: 21369148 DOI: 10.1364/oe.19.003258] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Recent work on high-power fiber amplifiers report on a degradation of the output beam quality or even on the appearance of mode instabilities. By combining the transversally resolved rate equations with a 3D Beam propagation method we have managed to create a model able to provide an explanation of what we believe is at the root of this effect. Even though this beam quality degradation is conventionally linked to transversal hole burning, our simulations show that this alone cannot explain the effect in very large mode area fibers. According to the model presented in this paper, the most likely cause for the beam quality degradation is an inversion-induced grating created by the interplay between modal interference along the fiber and transversal hole burning.
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Affiliation(s)
- Cesar Jauregui
- Friedrich-Schiller University Jena, Institute of Applied Physics, Albert Einstein-Strasse 15, D-07745, Jena, Germany.
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32
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Ye C, Montiel i Ponsoda JJ, Tervonen A, Honkanen S. Refractive index change in ytterbium-doped fibers induced by photodarkening and thermal bleaching. APPLIED OPTICS 2010; 49:5799-5805. [PMID: 20962944 DOI: 10.1364/ao.49.005799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
High-accuracy measurements and analysis of refractive index change induced by photodarkening and thermal bleaching in ytterbium-doped fibers are presented, based on a modal interference method. Photodarkening-induced refractive index change is positive at the ytterbium lasing wavelengths near 1080 nm, and it approaches a saturated level, which is in the order of 10(-6)∼10(-5) for the tested fiber samples. It is found that the value of this refractive index change is linearly proportional to the photodarkening-induced excess loss at an arbitrary probe wavelength in the visible band. Thermal bleaching can only partially erase the photodarkening-induced refractive index change, leaving a residual index change of (0.2∼0.3)×10(-5). The influence of the photodarkening-induced refractive index change on fiber lasers is discussed.
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Affiliation(s)
- Changgeng Ye
- Department of Micro and Nanosciences, Aalto University, PL 13500, 00076 Aalto, Finland.
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33
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Nicholson JW, Fini JM, DeSantolo AM, Monberg E, DiMarcello F, Fleming J, Headley C, DiGiovanni DJ, Ghalmi S, Ramachandran S. A higher-order-mode erbium-doped-fiber amplifier. OPTICS EXPRESS 2010; 18:17651-17657. [PMID: 20721151 DOI: 10.1364/oe.18.017651] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We demonstrate the first erbium-doped fiber amplifier operating in a single, large-mode area, higher-order mode. A high-power, fundamental-mode, Raman fiber laser operating at 1480 nm was used as a pump source. Using a UV-written, long-period grating, both pump and 1564 nm signal were converted to the LP(0,10) mode, which had an effective area of 2700 microm(2) at 1550 nm. A maximum output power of 5.8 W at 1564 nm with more than 20 dB of gain in a 2.68 m long amplifier was obtained. The mode profile was undistorted at the highest output power.
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Affiliation(s)
- J W Nicholson
- OFS Laboratories, 19 Schoolhouse Road, Suite 105, Somerset, NJ 08873, USA.
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34
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Zhuang WZ, Huang WC, Huang YP, Su KW, Chen YF. Passively Q-switched photonic crystal fiber laser and intracavity optical parametric oscillator. OPTICS EXPRESS 2010; 18:8969-8975. [PMID: 20588742 DOI: 10.1364/oe.18.008969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report on a passively Q-switched photonic crystal fiber (PCF) laser with Cr(4+):YAG as a saturable absorber. Under a pump power of 14.2 W, the maximum pulse energy is up to 630 microJ with a pulse width of 36 ns at a repetition rate of 5.6 kHz. With an intracavity optical parametric oscillator, the passively Q-switched PCF laser is used to generate the signal wave at 1515 nm. The output pulse energy of the signal wave is found to be 140 microJ with a pulse width as short as 1.0 ns at a repetition rate of 3.3 kHz. The very short pulse width leads to the peak power up to 140 kW.
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Affiliation(s)
- W Z Zhuang
- Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
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35
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Her TH, Ao X, Casperson LW. Gain saturation in gain-guided slab waveguides with large-index antiguiding. OPTICS LETTERS 2009; 34:2411-2413. [PMID: 19684799 DOI: 10.1364/ol.34.002411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We investigate numerically and analytically the effects of gain saturation on the propagation of the fundamental mode in a gain-guided index-antiguided slab waveguide. The propagating mode adapts to gain saturation by becoming less confined, while at the same time its peak intensity increases more slowly. At steady state, both the mode shape and the power remain constant.
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Affiliation(s)
- Tsing-Hua Her
- Department of Physics and Optical Science, and Center for Optoelectronics and Optical Communications,The University of North Carolina at Charlotte, 9201 University City Boulevard,Charlotte, North Carolina 28223, USA.
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36
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Fu L, McKay HA, Dong L. Extremely large mode area optical fibers formed by thermal stress. OPTICS EXPRESS 2009; 17:11782-11793. [PMID: 19582093 DOI: 10.1364/oe.17.011782] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report a strictly single-mode optical fiber with a record core diameter of 84 microm and an effective mode area of approximately 3600 microm(2) at 1 microm. We also demonstrate fundamental mode operation in an optical fiber with a record core diameter of 252 microm and a measured mode field diameter (MFD) of 149 microm at 1.03 microm, i.e. an effective mode area (Aeff) of approximately 17,400 microm(2) at 1.03 microm, an Aeff of 31,600 microm(2) at 1.5 microm. All these fibers have near parabolic index profiles with a peak refractive index difference DeltaN approximately approximately 6 x 10(-5), i.e. a record low numerical aperture (NA) of approximately 0.013 in an optical fiber. This low refractive index difference was achieved by frozen-in thermal stress as a result of two different types of glass in the fibers. When the fundamental mode was excited in the 252 microm core fiber using a 1.03 microm ASE source, the output beam was measured to have M2x = 1.04 and M2y = 1.18.
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Affiliation(s)
- Libin Fu
- IMRA America Inc, Ann Arbor, MI 48105, USA.
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37
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Suzuki S, McKay HA, Peng X, Fu L, Dong L. Highly ytterbium-doped silica fibers with low photo-darkening. OPTICS EXPRESS 2009; 17:9924-9932. [PMID: 19506642 DOI: 10.1364/oe.17.009924] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Phosphorus co-doping is known to reduce clustering levels of rare earth ions in silica hosts. In this paper, ytterbium-doped silica fibers with approximately 8.9 wt% Yb(2)O(3), up to approximately 4700 dB/m peak core absorption at 976 nm, and low photo-darkening are demonstrated using high phosphorus co-doping. Measured gain as high as approximately 7 dB/cm is demonstrated in the fiber.
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38
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Dong L, McKay HA, Fu L, Ohta M, Marcinkevicius A, Suzuki S, Fermann ME. Ytterbium-doped all glass leakage channel fibers with highly fluorine-doped silica pump cladding. OPTICS EXPRESS 2009; 17:8962-8969. [PMID: 19466146 DOI: 10.1364/oe.17.008962] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
All glass leakage channel fibers have been demonstrated to be a potential practical solution for power scaling in fiber lasers beyond the nonlinear limits in conventional large mode area fibers. The all glass nature with absence of any air holes is especially useful for allowing the fibers to be used and fabricated much like conventional fibers. Previously, double clad active all glass leakage channel fibers used low index polymer as a pump guide with the drawbacks of being less reliable at high pump powers and not being able to change fiber outer diameter independent of pump guide dimension. In this work, we demonstrate, for the first time, ytterbium-doped double clad all glass leakage channel fibers with highly fluorine-doped silica as pump cladding. The new all glass leakage channel fibers have no polymer in the pump path and have independent control of fiber outer diameters and pump cladding dimension, and, therefore, enable designs with smaller pump guide for high pump absorption and, at the same time, with large fiber diameters to minimize micro and macro bending effects, a much desired features for large core fibers where intermodal coupling can be an issue due to a much increased mode density. An ytterbium-doped double clad PM fiber with core diameter of 80 microm is also reported, which can be coiled in 76 cm diameter coils.
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Affiliation(s)
- Liang Dong
- IMRA America Inc., 1044 Woodridge Avenue, Ann Arbor, MI 48105, USA.
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39
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Filippov V, Chamorovskii Y, Kerttula J, Kholodkov A, Okhotnikov OG. 600 W power scalable single transverse mode tapered double-clad fiber laser. OPTICS EXPRESS 2009; 17:1203-1214. [PMID: 19188947 DOI: 10.1364/oe.17.001203] [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
Pump propagation and absorption in active tapered double-clad fiber has been analyzed based on a ray optics approach. Optimization of the longitudinal shape, absorption and angular distribution of the pump beam allowed for power scaling of a ytterbium fiber laser up to 600 W with high beam quality (M2<or=1.08) and a slope efficiency of 63%. It is shown that the influence of vignetting in a tapered fiber can be avoided, resulting in high overall efficiency, in good agreement with the presented model.
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Affiliation(s)
- V Filippov
- Optoelectronics Research Centre, Tampere University of Technology, 33101 Tampere, Finland.
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40
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Hädrich S, Rothhardt J, Röser F, Gottschall T, Limpert J, Tünnermann A. Degenerate optical parametric amplifier delivering sub 30 fs pulses with 2GW peak power. OPTICS EXPRESS 2008; 16:19812-19820. [PMID: 19030067 DOI: 10.1364/oe.16.019812] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Degenerated optical parametric amplification (OPA) is a well known technique to achieve broadband amplification necessary to generate ultrashort pulses. Here we present a parametric amplifier pumped by the frequency doubled output of a state-of-the-art fiber chirped pulse amplification system (FCPA) delivering mJ pulse energy at 30 kHz repetition rate and 650 fs pulse duration. The parametric amplifier and the FCPA system are both seeded by the same Yb:KGW oscillator. Additional spectral broadening of the OPA seed provides enough bandwidth for the generation of ultrashort pulses. After amplification in two 1mm BBO crystals a pulse energy of 90 microJ is yielded at 30 kHz. Subsequent compression with a sequence of chirped mirrors shortens the pulses to 29 fs while the pulse energy is as high as 81 microJ resulting in 2GW of peak power.
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Affiliation(s)
- S Hädrich
- Friedrich Schiller University Jena, Institute of Applied Physics, Albert-Einstein-Str. 15, 07745 Jena, Germany.
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41
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Yang XL, Cai LZ, Wang YR, Dong GY, Shen XX, Meng XF, Hu Y. Large complete bandgaps in a two-dimensional square photonic crystal with isolated single-atom dielectric rods in air. NANOTECHNOLOGY 2008; 19:025201. [PMID: 21817535 DOI: 10.1088/0957-4484/19/02/025201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
It is well known that the square lattice of isolated single-atom dielectric rods in air does not give rise to complete bandgaps even when asymmetry is introduced to lift some degeneracy. However, in this paper, a new kind of two-dimensional square photonic crystal with isolated single-atom dielectric rods in air formed by holographic lithography is proposed, and the relation between their photonic bandgap properties and their specific holographic design are systematically analyzed. In addition to the large complete relative bandgap, namely 9.68% gap/midgap ratio for the dielectric constant contrast of 13.6:1, this structure has very large tolerance on the system parameters and fabrication conditions. This fact can greatly relax the experimental requirements. This work may demonstrate the unique feature and advantages of photonic crystals made by the holographic method and provide a guideline for their design and fabrication.
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Affiliation(s)
- X L Yang
- Department of Optics, Shandong University, Jinan 250100, People's Republic of China
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42
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Michaille L, Taylor DM, Bennett CR, Shepherd TJ, Ward BG. Characteristics of a Q-switched multicore photonic crystal fiber laser with a very large mode field area. OPTICS LETTERS 2008; 33:71-73. [PMID: 18157262 DOI: 10.1364/ol.33.000071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We model and characterize the behavior of a Q-switched fiber laser. The fiber is a doped multicore photonic crystal fiber having six cores in a ring-type geometry. The fiber laser is Q-switched using an intracavity acousto-optic modulator. Using a mode filtering technique in the far field, a mode very close to the fundamental in-phase supermode is obtained with a mode field area of 4200 microm(2) and a divergence of 9 mrad. Pulses with energies of up to 2.2 mJ and durations of 26 ns (limited by end facet damage) at a repetition rate of 10 kHz are obtained.
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43
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Mortensen NA. Air-clad fibers: pump absorption assisted by chaotic wave dynamics? OPTICS EXPRESS 2007; 15:8988-8996. [PMID: 19547238 DOI: 10.1364/oe.15.008988] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Wave chaos is a concept which has already proved its practical usefulness in design of double-clad fibers for cladding-pumped fiber lasers and fiber amplifiers. In general, classically chaotic geometries will favor strong pump absorption and we address the extent of chaotic wave dynamics in typical air-clad geometries. While air-clad structures supporting sup-wavelength convex air-glass interfaces (viewed from the high-index side) will promote chaotic dynamics we find guidance of regular whispering-gallery modes in air-clad structures resembling an overall cylindrical symmetry. Highly symmetric air-clad structures may thus suppress the pump-absorption efficiency eta below the ergodic scaling law etainfinity Ac/Acl, where Ac and Acl are the areas of the rare-earth doped core and the cladding, respectively.
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Fini JM. Intuitive modeling of bend distortion in large-mode-area fibers. OPTICS LETTERS 2007; 32:1632-4. [PMID: 17572729 DOI: 10.1364/ol.32.001632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Bend distortion is emerging as an important consideration in the design of amplifier fibers with a large mode area, in addition to bend loss and mode-coupling effects. Simple, intuitive estimates of distortion sensitivity are presented for two interesting classes of fibers, in agreement with full numerical simulations.
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45
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Schmidt O, Rothhardt J, Röser F, Linke S, Schreiber T, Rademaker K, Limpert J, Ermeneux S, Yvernault P, Salin F, Tünnermann A. Millijoule pulse energy Q-switched short-length fiber laser. OPTICS LETTERS 2007; 32:1551-3. [PMID: 17546185 DOI: 10.1364/ol.32.001551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We report on a Q-switched short-length fiber laser producing 100 W of average output power at 100 kHz repetition rate and pulse durations as short as 17 ns. Up to 2 mJ of energy and sub-10-ns pulse duration are extracted at lower repetition rates. This performance is obtained by employing a rod-type ytterbium-doped photonic crystal fiber with a 70 microm core as gain medium, allowing for very short pulse durations, high energy storage, and emission of a single-transverse-mode beam.
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Affiliation(s)
- O Schmidt
- Friedrich Schiller University Jena, Institute of Applied Physics, Albert-Einstein-Strasse 15, Jena, Germany.
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Manek-Hönninger I, Boullet J, Cardinal T, Guillen F, Ermeneux S, Podgorski M, Bello Doua R, Salin F. Photodarkening and photobleaching of an ytterbium-doped silica double-clad LMA fiber. OPTICS EXPRESS 2007; 15:1606-1611. [PMID: 19532394 DOI: 10.1364/oe.15.001606] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We studied the temporal evolution of the photodarkening effect in an Yb-doped silica LMA fiber. The absorption spectra exhibit an increase in absorption in the visible and in the near infrared spectral range when the fiber is exposed to pump light around 980 nm. We show the influence of the photodarkening on the cw lasing properties of the fiber, and demonstrate photobleaching of the same fiber by exposure to UV light at 355 nm. The corresponding absorption spectra and lasing performances are shown and are entirely comparable to those of a new fiber.
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47
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Ramachandran S, Nicholson JW, Ghalmi S, Yan MF, Wisk P, Monberg E, Dimarcello FV. Light propagation with ultralarge modal areas in optical fibers. OPTICS LETTERS 2006; 31:1797-9. [PMID: 16729074 DOI: 10.1364/ol.31.001797] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We demonstrate robust single-transverse-mode light propagation in higher-order modes of a fiber, with effective area A(eff) ranging from 2,100 to 3,200 microm(2). These modes are accessed using long-period fiber gratings that enable higher-order-mode excitation over a bandwidth of 94 mm with greater than 99% of the light in the desired mode. The fiber is designed such that the effective index separation between modes is always large, hence minimizing in-fiber mode mixing and enabling light propagation over lengths as large as 12 m, with bends down to 4.5 cm radii. The modal stability increases with mode order, suggesting that A(eff) of this platform is substantially scalable.
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Affiliation(s)
- S Ramachandran
- OFS Laboratories, 25 Schoolhouse Road, Somerset, New Jersey 08873, USA.
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48
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Schreiber T, Nielsen CK, Ortac B, Limpert J, Tünnermann A. Microjoule-level all-polarization-maintaining femtosecond fiber source. OPTICS LETTERS 2006; 31:574-6. [PMID: 16570402 DOI: 10.1364/ol.31.000574] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We report on a high-power, high-energy femtosecond fiber source based on direct amplification of parabolic pulses from an environmentally stable passively mode-locked fiber oscillator in an Yb-doped single-polarization photonic crystal fiber. The special pulse shape allows for the generation of high-quality femtosecond pulses beyond nonlinearity limits. The system delivers a pulse energy of 1.2 microJ (21 W average power) at a repetition rate of 17 MHz and a pulse duration of 240 fs in a linearly polarized beam with diffraction-limited quality.
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Affiliation(s)
- Thomas Schreiber
- Friedrich Schiller University, Institute of Applied Physics, Max-Wien-Platz 1, D-07743 Jena, Germany.
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