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Demirkhanyan G, Patrizi B, Kostanyan R, Li J, Pirri A, Feng Y, Xie T, Wu L, Vannini M, Becucci M, Zargaryan D, Toci G. Evidence of two Yb3+ crystallographic sites occupancy in Y3Al5O12 ceramics from an in depth spectroscopic analysis. J SOLID STATE CHEM 2022. [DOI: 10.1016/j.jssc.2022.123577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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2
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Strain Control of Magnetic Anisotropy in Yttrium Iron Garnet Films in a Composite Structure with Yttrium Aluminum Garnet Substrate. JOURNAL OF COMPOSITES SCIENCE 2022. [DOI: 10.3390/jcs6070203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This report is on the nature of strain in thin films of yttrium iron garnet (YIG) on yttrium aluminum garnet (YAG) substrates due to film-substrate lattice mismatch and the resulting induced magnetic anisotropy. Films with thickness 55 nm to 380 nm were deposited on (100), (110), and (111) YAG substrates using pulsed laser deposition (PLD) techniques and characterized by structural and magnetic characterization techniques. The in-plane strain determined to be compressive using X-ray diffraction (XRD). It varied from −0.12% to −0.98% and increased in magnitude with increasing film thickness and was relatively large in films on (100) YAG. The out-of-plane strain was tensile and also increased with increasing film thickness. The estimated strain-induced magnetic anisotropy field, found from XRD data, was out of plane; its value increased with film thickness and ranged from 0.47 kOe to 3.96 kOe. Ferromagnetic resonance (FMR) measurements at 5 to 21 GHz also revealed the presence of a perpendicular magnetic anisotropy that decreased with increasing film thickness and its values were smaller than values obtained from XRD data. The PLD YIG films on YAG substrates exhibiting a perpendicular anisotropy field have the potential for use in self-biased sensors and high-frequency devices.
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Strain induced anisotropy in liquid phase epitaxy grown nickel ferrite on magnesium gallate substrates. Sci Rep 2022; 12:7052. [PMID: 35488114 PMCID: PMC9054777 DOI: 10.1038/s41598-022-10814-8] [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: 07/30/2021] [Accepted: 04/05/2022] [Indexed: 12/04/2022] Open
Abstract
This work focuses on the nature of magnetic anisotropy in 2.5–16 micron thick films of nickel ferrite (NFO) grown by liquid phase epitaxy (LPE). The technique, ideal for rapid growth of epitaxial oxide films, was utilized for films on (100) and (110) substrates of magnesium gallate (MGO). The motivation was to investigate the dependence of the growth induced anisotropy field on film thickness since submicron films of NFO were reported to show a very high anisotropy. The films grown at 850–875 C and subsequently annealed at 1000 C were found to be epitaxial, with the out-of-plane lattice constant showing unanticipated decrease with increasing film thickness and the estimated in-plane lattice constant increasing with the film thickness. The uniaxial anisotropy field Hσ, estimated from X-ray diffraction data, ranged from 2.8–7.7 kOe with the films on (100) MGO having a higher Hσ value than for the films on (110) MGO. Ferromagnetic resonance (FMR) measurements for in-plane and out-of-plane static magnetic field were utilized to determine both the magnetocrystalline the anisotropy field H4 and the uniaxial anisotropy field Ha. Values of H4 range from −0.24 to −0.86 kOe. The uniaxial anisotropy field Ha was an order of magnitude smaller than Hσ and it decreased with increasing film thickness for NFO films on (100) MGO, but Ha increased with film thickness for films on (110) MGO substrates. These observations indicate that the origin of the induced anisotropy could be attributed to several factors including (i) strain due to mismatch in the film-substrate lattice constants, (ii) possible variations in the bond lengths and bond angles in NFO during the growth process, and (iii) the strain arising from mismatch in the thermal expansion coefficients of the film and the substrate due to the high growth and annealing temperatures involved in the LPE technique. The LPE films of NFO on MGO substrates studied in this work are of interest for use in high frequency devices.
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Surface Shape Distortion Online Measurement Method for Compact Laser Cavities Based on Phase Measuring Deflectometry. PHOTONICS 2022. [DOI: 10.3390/photonics9030151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Conventional phase measuring deflectometry (PMD) takes up a large measurement space and is not suitable for compact online measurement, as the liquid crystal display (LCD) has to be placed in parallel with the mirror under test. In this paper, a compact online phase measuring deflectometry (COPMD) with the LCD screen set perpendicular to the mirror under test is presented for surface shape distortion real-time measurement. The configuration of the COPMD in an enclosed laser cavity is proposed, and the principle of the method is theoretically derived by using the vector-form reflection law. Based on the analysis model, the fringe modulation regulation of the LCD is revealed, and the measurement errors caused by misalignments of the components are illustrated. The validity and flexibility of the COPMD method are verified in the experiment by using a single-actuator deformable mirror as the mirror under test and the PMD method as the comparison. The proposed COPMD method remarkably expands the application range of the conventional PMD method, as it could make efficient use of compact space and is applicable for real-time measurement in enclosed laser facilities and assembled laser systems.
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Wu J, Wan Y, Wang P, Zhang H, Wang X, Zhou P, Du S, Xu X. Wide temperature operation of kilowatt fiber oscillators. APPLIED OPTICS 2022; 61:417-421. [PMID: 35200878 DOI: 10.1364/ao.445911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 12/12/2021] [Indexed: 06/14/2023]
Abstract
To meet the requirements of fiber laser applications under extreme temperatures or when there is a large temperature difference, it is necessary to develop fiber lasers able to operate in a wide temperature range. At present, there is a lack of reports on high-power fiber lasers that can operate in a wide temperature range with low power fluctuations. Thus, we designed a 1 kW fiber oscillator that can operate in a wide temperature range through temperature-related rate equations. The output characteristics of the oscillator are measured in the operating temperature range from -30∘C to 20°C. The experimental results show that the laser output power fluctuates by 7% over the entire temperature range. It was discovered that as the ambient temperature decreased, the efficiency of the laser decreased, and this issue is discussed in detail. This work has guiding significance for the design of high-power fiber lasers operating at a wide temperature range, and simultaneously, to the best of our knowledge, it provides the first kilowatt fiber oscillator that can operate in a wide temperature range between -30∘C and 20°C.
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Zhu S, Li J, Li L, Sun K, Hu C, Shao X, Ma X. Mode instabilities in Yb:YAG crystalline fiber amplifiers. OPTICS EXPRESS 2019; 27:35065-35078. [PMID: 31878682 DOI: 10.1364/oe.27.035065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 11/05/2019] [Indexed: 06/10/2023]
Abstract
Mode instabilities (MI) threshold in the Yb:YAG crystalline fiber amplifier is simulated by a full numerical model. The propagation of signal fields is simulated by the finite-difference beam-propagation method combined with the rate equations, and the time-dependent heat equation is solved by the alternating-direction-implicit method. Considering the strong temperature-dependent laser performance of Yb:YAG, an iterative method is applied to reach the steady state of Yb:YAG, the crystalline fiber amplifier, before the simulation of MI behavior. The simulated MI thresholds in Yb:YAG crystalline fiber amplifiers are found to be at least 28 times of those in Yb-doped silica-glass fiber amplifiers, up to tens of kilowatts. Simulation results show that, in addition to the expected higher thermal conductivity and lower thermo-optic coefficient, strong gain saturation also plays an important role in the high MI threshold of the Yb:YAG crystalline fiber.
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Jiang X, Wang N, Molokeev MS, Wang W, Guo S, Huang R, Li L, Hu Z, Lin Z. The Anisotropic Thermal Expansion of Non-linear Optical Crystal BaAlBO 3F 2 Below Room Temperature. Front Chem 2018; 6:252. [PMID: 30003077 PMCID: PMC6033077 DOI: 10.3389/fchem.2018.00252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 06/08/2018] [Indexed: 11/30/2022] Open
Abstract
Thermal expansion is a crucial factor for the performance of laser devices, since the induced thermal stress by laser irradiation would strongly affect the optical beam quality. For BaAlBO3F2 (BABF), a good non-linear optical (NLO) crystal, due to the highly anisotropic thermal expansion its practical applications are strongly affected by the “tearing” stress with the presence of local overheating area around the laser spot. Recently, the strategy to place the optical crystals in low-temperature environment to alleviate the influence of the thermal effect has been proposed. In order to understand the prospect of BABF for this application, in this work, we investigated its thermal expansion behavior below room temperature. The variable-temperature XRD showed that the ratio of thermal expansion coefficient between along c- and along a(b)- axis is high as 4.5:1 in BABF. The Raman spectrum combined with first-principles phonon analysis revealed that this high thermal expansion anisotropy mainly ascribe to progressive stimulation of the respective vibration phonon modes related with the thermal expansion along a(b)- and c-axis. The good NLO performance in BABF can be kept below room temperature. The work presented in this paper provides an in-depth sight into the thermal expansion behavior in BABF, which, we believe, would has significant implication to the manipulation in atomic scale on the thermal expansion of the materials adopted in strong-field optical facility.
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Affiliation(s)
- Xingxing Jiang
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China
| | - Naizheng Wang
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China.,University of the Chinese Academy of Sciences, Beijing, China
| | - Maxim S Molokeev
- Laboratory of Crystal Physics, Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Krasnoyarsk, Russia.,Department of Physics, Far Eastern State Transport University, Khabarovsk, Russia.,Department of Engineering Physics and Radioelectronic, Siberian Federal University, Krasnoyarsk, Russia
| | - Wei Wang
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China
| | - Shibin Guo
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China
| | - Rongjin Huang
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China
| | - Laifeng Li
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China
| | - Zhanggui Hu
- Institute of Functional Crystals, Tianjin University of Technology, Tianjin, China
| | - Zheshuai Lin
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China.,University of the Chinese Academy of Sciences, Beijing, China
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8
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Ganija M, Hemming A, Simakov N, Boyd K, Haub J, Veitch P, Munch J. High power cryogenic Ho:YAG laser. OPTICS EXPRESS 2017; 25:31889-31895. [PMID: 29245858 DOI: 10.1364/oe.25.031889] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 12/04/2017] [Indexed: 06/07/2023]
Abstract
We have improved significantly the brightness of cryogenic Ho:YAG, reporting up to 65 W output power with a beam quality of M2 <1.3 and a slope efficiency of 71%. The laser emission was ~2 nm wide and centered at 2097.5 nm. This result demonstrates the scalability of both the narrow-line thulium fibre pump laser and the cryogenic laser head.
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9
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Cini L, Mackenzie JI. Analytical thermal model for end-pumped solid-state lasers. APPLIED PHYSICS. B, LASERS AND OPTICS 2017; 123:273. [PMID: 31997852 PMCID: PMC6956956 DOI: 10.1007/s00340-017-6848-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 09/21/2017] [Indexed: 06/08/2023]
Abstract
Fundamentally power-limited by thermal effects, the design challenge for end-pumped "bulk" solid-state lasers depends upon knowledge of the temperature gradients within the gain medium. We have developed analytical expressions that can be used to model the temperature distribution and thermal-lens power in end-pumped solid-state lasers. Enabled by the inclusion of a temperature-dependent thermal conductivity, applicable from cryogenic to elevated temperatures, typical pumping distributions are explored and the results compared with accepted models. Key insights are gained through these analytical expressions, such as the dependence of the peak temperature rise in function of the boundary thermal conductance to the heat sink. Our generalized expressions provide simple and time-efficient tools for parametric optimization of the heat distribution in the gain medium based upon the material and pumping constraints.
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Affiliation(s)
- L. Cini
- Dipartimento di Fisica, Università di Pisa, Largo B. Pontecorvo 3, Pisa, 56127 Italy
- Optoelectronics Research Centre, University of Southampton, Highfield Southampton SO17 1BJ, Southampton, United Kingdom
| | - J. I. Mackenzie
- Optoelectronics Research Centre, University of Southampton, Highfield Southampton SO17 1BJ, Southampton, United Kingdom
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10
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Graumann IJ, Diebold A, Alfieri CGE, Emaury F, Deppe B, Golling M, Bauer D, Sutter D, Kränkel C, Saraceno CJ, Phillips CR, Keller U. Peak-power scaling of femtosecond Yb:Lu 2O 3 thin-disk lasers. OPTICS EXPRESS 2017; 25:22519-22536. [PMID: 29041561 DOI: 10.1364/oe.25.022519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 08/20/2017] [Indexed: 06/07/2023]
Abstract
We present a high-peak-power SESAM-modelocked thin-disk laser (TDL) based on the gain material Yb-doped lutetia (Yb:Lu2O3), which exceeds a peak-power of 10 MW for the first time. We generate pulses as short as 534 fs with an average power of 90 W and a peak power of 10.1 MW, and in addition a peak power as high as 12.3 MW with 616-fs pulses and 82-W average power. The center lasing wavelength is 1033 nm and the pulse repetition rates are around 10 MHz. We discuss and explain the current limitations with numerical models, which show that the current peak power is limited in soliton modelocking by the interplay of the gain bandwidth and the induced absorption in the SESAM with subsequent thermal lensing effects. We use our numerical model which is validated by the current experimental results to discuss a possible road map to scale the peak power into the 100-MW regime and at the same time reduce the pulse duration further to sub-200 fs. We consider Yb:Lu2O3 as currently the most promising gain material for the combination of high peak power and short pulse duration in the thin-disk-laser geometry.
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11
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Nemitz W, Fulmek P, Nicolics J, Reil F, Wenzl FP. On the determination of the temperature distribution within the color conversion elements of phosphor converted LEDs. Sci Rep 2017; 7:9964. [PMID: 28855702 PMCID: PMC5577217 DOI: 10.1038/s41598-017-10114-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 08/04/2017] [Indexed: 11/09/2022] Open
Abstract
We present an iterative optical and thermal simulation procedure which enables the determination of the temperature distribution in the phosphor layer of a phosphor converted LED with good accuracy. Using the simulation both the highest phosphor temperatures, which are mostly relevant to material degradation as well as the temperatures of those phosphor particles which mainly contribute to converted light emission can be determined. We compare the simulations with experimental studies on the phosphor temperature. While infrared thermography only gives information on the phosphor layer surface temperature, phosphor thermometry provides temperature data on the volume temperature of the phosphor layer relevant to color conversion.
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Affiliation(s)
- Wolfgang Nemitz
- Institute of Surface Technologies and Photonics, JOANNEUM RESEARCH Forschungsgesm.b.H., Franz-Pichler-Straße 30, A-8160, Weiz, Austria
| | - Paul Fulmek
- Institute of Sensor & Actuator Systems, TU Wien, Gusshausstraße 27-29, A-1040, Vienna, Austria
| | - Johann Nicolics
- Institute of Sensor & Actuator Systems, TU Wien, Gusshausstraße 27-29, A-1040, Vienna, Austria
| | - Frank Reil
- Institute of Surface Technologies and Photonics, JOANNEUM RESEARCH Forschungsgesm.b.H., Franz-Pichler-Straße 30, A-8160, Weiz, Austria
| | - Franz P Wenzl
- Institute of Surface Technologies and Photonics, JOANNEUM RESEARCH Forschungsgesm.b.H., Franz-Pichler-Straße 30, A-8160, Weiz, Austria.
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12
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Norimatsu T, Kawanaka J, Miyanaga M, Azechi H, Mima K, Furukawa H, Kozaki Y, Tomabechi K. Conceptual Design of Fast Ignition Power Plant KOYO-F Driven by Cooled Yb:YAG Ceramic Laser. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst52-893] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- T. Norimatsu
- Institute of Laser Engineering, Osaka University, Suita, Osaka,5650871, Japan
| | - J. Kawanaka
- Institute of Laser Engineering, Osaka University, Suita, Osaka,5650871, Japan
| | - M. Miyanaga
- Institute of Laser Engineering, Osaka University, Suita, Osaka,5650871, Japan
| | - H. Azechi
- Institute of Laser Engineering, Osaka University, Suita, Osaka,5650871, Japan
| | - K. Mima
- Institute of Laser Engineering, Osaka University, Suita, Osaka,5650871, Japan
| | - H. Furukawa
- Institute for Laser Engineering, Nishi-ku, Osaka, 5500004, Japan
| | - Y. Kozaki
- Institute for Fusion Science, Toki, Gifu 5095292, Japan
| | - K. Tomabechi
- IFE Forum, Institute for Laser Engineering, Nishi-ku, Osaka, 5500004, Japan
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13
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Huang TL, Sung CL, Cheng HP, Cho CY, Liang HC, Su KW, Huang KF, Chen YF. Synchronized self-mode-locked 1061-nm and 1064-nm monolithic Nd:YAG laser at cryogenic temperatures with two orthogonally polarized emissions: generation of 670 GHz beating. OPTICS EXPRESS 2016; 24:22189-22197. [PMID: 27661953 DOI: 10.1364/oe.24.022189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A dual-wavelength self-mode-locked monolithic Nd:YAG laser at 1061 and 1064 nm is realized at cryogenic temperatures. At an incident pump power of 5.5 W, the total output power can reach 2.5 W and the mode-locked pulse width is 29 ps at a pulse repetition rate of 7.75 GHz. The synchronization of the dual-wavelength emissions leads to a beat frequency of 670 GHz in the individual mode-locked pulse. It is further discovered that the laser output consists of two orthogonally polarized components with a central frequency difference of 127 MHz. The central frequency difference between two orthogonal polarizations mainly arises from the external mechanical stress introduced by the copper holder for the laser crystal.
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14
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Ganija M, Simakov N, Hemming A, Haub J, Veitch P, Munch J. Efficient, low threshold, cryogenic Ho:YAG laser. OPTICS EXPRESS 2016; 24:11569-11577. [PMID: 27410084 DOI: 10.1364/oe.24.011569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report the development of an efficient, liquid-nitrogen conduction cooled Ho:YAG slab laser with good beam quality. Detailed measurements resolving the structure of the 1900-1911 nm absorption band in Ho:YAG at 77 K are presented. Stress-free conduction cooled mounting of the Ho:YAG slab was demonstrated and the resulting laser operated with a large mode volume of 42 mm3, a slope efficiency of 75% and a threshold of 0.84 W. To our knowledge this corresponds to the lowest reported threshold intensity for a Ho:YAG laser.
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15
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The Application of Cryogenic Laser Physics to the Development of High Average Power Ultra-Short Pulse Lasers. APPLIED SCIENCES-BASEL 2016. [DOI: 10.3390/app6010023] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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16
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Cho CY, Huang TL, Cheng HP, Huang KF, Chen YF. Analysis of the optimal temperature for the cryogenic monolithic Nd:YAG laser at 946-nm. OPTICS EXPRESS 2016; 24:1-8. [PMID: 26832232 DOI: 10.1364/oe.24.000001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The optimal temperature for the cryogenic monolithic Nd:YAG laser at 946-nm is theoretically and experimentally analyzed. It is clear that decreasing temperature can considerably eliminate the thermal population at the lower laser level to enhance the quantum efficiency. However, the narrowing of the absorption bandwidth for the gain medium leads to a reduction of the effective absorption efficiency as the temperature is decreased. Consequently, an optimal temperature for the maximum output power is found to be in the range of approximately 120 K to 140 K. It is experimentally verified that employing a pump source with a narrower emission spectrum linewidth contributes a more efficient output for the cryogenic laser.
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17
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Wang Y, Zhang R, Li J, Li W. Optimization of pump size in a solid-state laser considering the temperature distribution in a laser medium. APPLIED OPTICS 2015; 54:8087-8090. [PMID: 26406509 DOI: 10.1364/ao.54.008087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The influences of the temperature distribution of a laser medium on thermal effects, especially on the thermally induced diffraction losses, have been investigated in this paper. The results show that the thermally induced diffraction losses are decreasing functions of the pump beam radius for identical mode-to-pump ratios in the laser medium, but it is approximately constant if the real temperature is neglected. Applying this theoretical model to a diode-end-pumped Nd:GdVO4 laser at 1342 nm, the pump size was optimized to scale the output power, and the theoretical results are in good agreement with the experimental results.
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18
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Tang B, Zhou T, Wang D, Li M. Optical distortions in end-pumped zigzag slab lasers. APPLIED OPTICS 2015; 54:2693-2702. [PMID: 25967178 DOI: 10.1364/ao.54.002693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 02/19/2015] [Indexed: 06/04/2023]
Abstract
Ray tracing is performed to investigate the optical distortions in the end-pumped, zigzag slab. Optical path differences caused by temperature, slab deformation, and stress birefringence are calculated under uniform pumping; the results show a steep edge in the width dimension and a thermal lens with an effective focal length as short as several meters in the thickness dimension. Dependence of depolarization on total internal reflection phase retardance as well as the slab's cut angle is studied by the Jones matrix technique; results show that although at the pumping power of 10 kW, the mean depolarization of the 2.5 mm×30 mm×150.2 mm Nd:YAG slab is generally below 3%, and it increases rapidly with pumping power. Besides, for the 0°- or 60°-cut slab, an optimal phase retardance range of 5° to 13° exists, in which the depolarization loss can be lower than 0.5%. Finally, experiments on temperature and depolarization measurements verify the numerical results.
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19
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Albach D, Chanteloup JC. Large size crystalline vs. co-sintered ceramic Yb(3+):YAG disk performance in diode pumped amplifiers. OPTICS EXPRESS 2015; 23:570-579. [PMID: 25835703 DOI: 10.1364/oe.23.000570] [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
A comprehensive experimental benchmarking of Yb(3+):YAG crystalline and co-sintered ceramic disks of similar thickness and doping level is presented in the context of high average power laser amplifier operation. Comparison is performed considering gain, depolarization and wave front deformation quantitative measurements and analysis.
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20
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Polok K, Ratajska-Gadomska B, Konarska J, Gadomski W. Coherent optical phonons in pure and Pr3+ doped YAG crystal studied by Optical Kerr Effect spectroscopy: Temperature and concentration dependence. Chem Phys 2014. [DOI: 10.1016/j.chemphys.2014.02.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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21
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Yasuhara R, Nozawa H, Yanagitani T, Motokoshi S, Kawanaka J. Temperature dependence of thermo-optic effects of single-crystal and ceramic TGG. OPTICS EXPRESS 2013; 21:31443-31452. [PMID: 24514718 DOI: 10.1364/oe.21.031443] [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
The temperature dependence of the thermo-optic effects in single crystal and ceramic TGG were evaluated by using the Fizou interferometer method. The temperature dependence of the refractive index and thermal expansion are significantly improved at low temperature for both ceramics and single crystals. Our estimation using a figure of merit indicated that a TGG ceramics cooled to liquid nitrogen temperature can reduce thermal wave-front distortion by a factor of up to 4.7 with respect to that at 300 K, and can reduce thermal birefringence effects by up to a factor of 12 with respect to those at 300 K.
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Ganija M, Ottaway D, Veitch P, Munch J. Cryogenic, high power, near diffraction limited, Yb:YAG slab laser. OPTICS EXPRESS 2013; 21:6973-6978. [PMID: 23546080 DOI: 10.1364/oe.21.006973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A cryogenic slab laser that is suitable for scaling to high power, while taking full advantage of the improved thermo-optical and thermo-mechanical properties of Yb:YAG at cryogenic temperatures is described. The laser uses a conduction cooled, end pumped, zigzag slab geometry resulting in a near diffraction limited, robust, power scalable design. The design and the initial characterization of the laser up to 200W are presented.
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Affiliation(s)
- Miftar Ganija
- School of Chemistry and Physics and IPAS, The University of Adelaide, SA 5005, Australia.
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23
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Reddy BR, Kamma I, Kommidi P. Optical sensing techniques for temperature measurement. APPLIED OPTICS 2013; 52:B33-B39. [PMID: 23385939 DOI: 10.1364/ao.52.000b33] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 11/26/2012] [Indexed: 06/01/2023]
Abstract
Temperature is an important parameter that needs accurate measurement. Theoretical descriptions of the fluorescence ratio method, fluorescence lifetime sensing, and interferometric methods for temperature measurement are given. Fluorescence lifetime sensing calibration plots have been developed for temperature measurement from 20°C to 600°C using Er(3+)-doped glass, and from 20°C to 90°C using Sm(3+)-doped CaF(2). Lifetime sensing results of Pr(3+)-doped YAG and Ho(3+)-doped fluoride crystals for temperature measurement are also summarized. Mach-Zehnder interferometer measurements revealed that the passage of a 300 mW laser beam of 915 nm changed the temperature of the Yb(3+)-doped YAG crystal by 7.1°C. The interferometer technique is useful for measuring absolute temperature changes in laser cooling studies.
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Affiliation(s)
- B Rami Reddy
- Department of Physics, Alabama A&M University, Normal, Alabama 35762, USA.
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Yasuhara R, Furuse H, Iwamoto A, Kawanaka J, Yanagitani T. Evaluation of thermo-optic characteristics of cryogenically cooled Yb:YAG ceramics. OPTICS EXPRESS 2012; 20:29531-29539. [PMID: 23388780 DOI: 10.1364/oe.20.029531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The temperature dependence of the thermo-optic effect in cryogenically cooled Yb:YAG ceramics was evaluated by measuring the thermo-optic coefficient (the derivative of refractive index with respect to temperature, i.e., dn/dT), thermal expansion coefficient (α), and thermal conductivity (κ) between 70 and 300 K. These parameters significantly improved at low temperature. Observed values indicated that a laser gain medium cooled to 70 K can sustain a thermal load up to 20 times higher than that at 300 K, for comparable thermo-optic effects. To our best knowledge, this is the first quantitative evaluation of the improvement in thermo-optic characteristics of cryogenically cooled Yb:YAG ceramics.
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Affiliation(s)
- Ryo Yasuhara
- National Institute for Fusion Science, 322-6, Oroshi-cho, Toki, Gifu 509-5292, Japan.
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25
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Farley CW, Reddy BR. Interferometric measurement of laser heating in praseodymium-doped YAG crystal. APPLIED OPTICS 2011; 50:526-531. [PMID: 21283244 DOI: 10.1364/ao.50.000526] [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
Temperature measurement is required for many applications but can be difficult in some cases. Laser heating or cooling studies demand accurate measurements of temperature changes. A Michelson interferometer configuration has been used to investigate laser heating in solids. An analytical formula was derived to estimate the temperature change from the fringe count by taking into account the temperature dependence of the sample length and refractive index. When 115 mW of a focused Ar+ laser beam (488 nm) passes through a Pr(3+)-doped YAG sample, its temperature increased by 11.7±1.0 K along the beam path due to nonradiative relaxation. The power dependence of the fringe count/movement was recorded. The temperature change was estimated by the interferometric method and is in agreement with that measured by a thermocouple.
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Affiliation(s)
- Carlton W Farley
- Department of Physics, Alabama A&M University, Normal, Alabama 35762, USA
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26
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Scholz M, Kovalchuk E, Peters A. Frequency characteristics of an inherently stable Nd:YAG laser operated at liquid helium temperature. APPLIED OPTICS 2009; 48:3938-3942. [PMID: 19593345 DOI: 10.1364/ao.48.003938] [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 report on frequency measurements of a free-running Nd:YAG laser operating at temperatures down to 6.5 K using a femtosecond laser frequency comb. Due to lower thermal expansion and thermo-optic effects as well as reduced electron-phonon interactions in Nd:YAG at cryogenic temperatures, a laser frequency stability on the order of 10(-11) at tau < or = 30s has been achieved. Within a one-week measurement period, absolute frequency deviations were lower than 1.85 MHz. This is up to a 100-fold improvement of frequency stability compared to any existing free-running solid-state laser.
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Affiliation(s)
- Matthias Scholz
- Institut für Physik, Humboldt-Universität zu Berlin, Hausvogteiplatz 5-7, 10117 Berlin, Germany.
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27
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Yao BQ, Duan XM, Fang D, Zhang YJ, Ke L, Ju YL, Wang YZ, Zhao GJ. 7.3 W of single-frequency output power at 2.09 mum from an Ho:YAG monolithic nonplanar ring laser. OPTICS LETTERS 2008; 33:2161-2163. [PMID: 18794964 DOI: 10.1364/ol.33.002161] [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
Single-frequency output power of 7.3 W at 2.09 mum from a monolithic Ho:YAG nonplanar ring oscillator (NPRO) is demonstrated. Resonantly pumped by a Tm-doped fiber laser at 1.91 mum, the Ho:YAG NPRO produces 71% of slope efficiency with respect to absorbed pump power and nearly diffraction-limited output with a beam quality parameter of M(2) approximately 1.1.
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Affiliation(s)
- Bao-Quan Yao
- National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin, China.
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28
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Yu H, Bourdet G, Ferre S. Comprehensive modeling of the temperature-related laser performances of the amplifiers of the LUCIA laser. APPLIED OPTICS 2005; 44:6412-8. [PMID: 16255089 DOI: 10.1364/ao.44.006412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We present numerical simulations of the temperature-related laser performance of the amplifiers for the Lasers Ultra-Courts et Intenses et Applications (LUCIA) laser, a 100 J, 10 Hz, 10 ns diode-pumping solid-state-laser facility, which uses Yb3+:YAG as the gain medium. The simulations include energy storage and extraction efficiency, cooling of the gain medium, and wavefront distortion. The results show that, with a pumping intensity of 20 kW/cm2 at 10 Hz and a doping concentration of 10 at. % at a thickness of Yb3+:YAG of 1.6 mm, the output laser fluence and optical-to-optical efficiency are expected to be 10 J/cm2 and 25.8%, respectively, at a heat exchange coefficient of 3000 W/m2/K of water. Also, the matching thickness of undoped YAG is optimized to prevent bending deformation of the gain medium, which could be approximately 5 mm.
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Affiliation(s)
- Haiwu Yu
- Laboratoire pour l'Utilisation des Lasers Intense, Unité Mixte de Recherche 7605, Ecole Polytechnique--Centre National de la Recherche Scientifique, Commissariat a L'Energie Atomique, Ecole Polytechnique, 91128 Palaiseau Cedex, France
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29
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Ripin DJ, Ochoa JR, Aggarwal RL, Fan TY. 165-W cryogenically cooled Yb:YAG laser. OPTICS LETTERS 2004; 29:2154-2156. [PMID: 15460887 DOI: 10.1364/ol.29.002154] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Thermo-optic distortions often limit the beam quality and power scaling of high-average-power lasers. Cryogenically cooled Yb:YAG is used to efficiently generate 165 W of near-diffraction-limited beam from a power oscillator with negligible thermo-optic effects. End pumped with 215 W of incident pump power from two diode modules, the laser has an optical-optical efficiency of 76%, a slope efficiency of 85%, and an M2 value of 1.02.
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Affiliation(s)
- Daniel J Ripin
- MIT Lincoln Laboratory, 244 Wood Street, Lexington, Massachusetts 02420, USA.
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30
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Bjurshagen S, Koch R. Modeling of energy-transfer upconversion and thermal effects in end-pumped quasi-three-level lasers. APPLIED OPTICS 2004; 43:4753-4767. [PMID: 15352402 DOI: 10.1364/ao.43.004753] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
An analytical model of cw quasi-three-level lasers that includes the influence of energy-transfer upconversion (ETU) has been developed. The results of the general output modeling were applied to a laser with Gaussian beams, and rigorous numerical calculations have been made to study the influence of ETU on threshold, output power, spatial distribution of population-inversion density, and fractional thermal loading. The model was applied to a laser operating at 946 nm in Nd:YAG, where the dependence of laser-beam size on laser performance was investigated in particular. A simple model for the degradation of laser-beam quality from a transversally varying saturated gain is proposed that is in good agreement with measurements of the laser in a plane-plane cavity.
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Affiliation(s)
- Stefan Bjurshagen
- Laser Physics and Quantum Optics, Department of Physics, Royal Institute of Technology, 106 91 Stockholm, Sweden.
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