1
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Dufresne SKY, Zhdanovich S, Michiardi M, Guislain BG, Zonno M, Mazzotti V, O'Brien L, Kung S, Levy G, Mills AK, Boschini F, Jones DJ, Damascelli A. A versatile laser-based apparatus for time-resolved ARPES with micro-scale spatial resolution. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:033907. [PMID: 38517258 DOI: 10.1063/5.0176170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 02/28/2024] [Indexed: 03/23/2024]
Abstract
We present the development of a versatile apparatus for 6.2 eV laser-based time and angle-resolved photoemission spectroscopy with micrometer spatial resolution (time-resolved μ-ARPES). With a combination of tunable spatial resolution down to ∼11 μm, high energy resolution (∼11 meV), near-transform-limited temporal resolution (∼280 fs), and tunable 1.55 eV pump fluence up to 3 mJ/cm2, this time-resolved μ-ARPES system enables the measurement of ultrafast electron dynamics in exfoliated and inhomogeneous materials. We demonstrate the performance of our system by correlating the spectral broadening of the topological surface state of Bi2Se3 with the spatial dimension of the probe pulse, as well as resolving the spatial inhomogeneity contribution to the observed spectral broadening. Finally, after in situ exfoliation, we performed time-resolved μ-ARPES on a ∼30 μm flake of transition metal dichalcogenide WTe2, thus demonstrating the ability to access ultrafast electron dynamics with momentum resolution on micro-exfoliated materials.
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Affiliation(s)
- S K Y Dufresne
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - S Zhdanovich
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - M Michiardi
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - B G Guislain
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - M Zonno
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - V Mazzotti
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - L O'Brien
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - S Kung
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - G Levy
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - A K Mills
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - F Boschini
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Centre Énergie Matériaux Télécommunications, Institut National de la Recherche Scientifique, Varennes, Québec J3X 1S2, Canada
| | - D J Jones
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - A Damascelli
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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2
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Winchester AJ, Anderson TJ, Hite JK, Elmquist RE, Pookpanratana S. Methodology and implementation of a tunable deep-ultraviolet laser source for photoemission electron microscopy. Ultramicroscopy 2023; 253:113819. [PMID: 37549583 DOI: 10.1016/j.ultramic.2023.113819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 06/21/2023] [Accepted: 07/25/2023] [Indexed: 08/09/2023]
Abstract
Photoemission electron microscopy (PEEM) is a unique and powerful tool for studying the electronic properties of materials and surfaces. However, it requires intense and well-controlled light sources with photon energies ranging from the UV to soft X-rays for achieving high spatial resolution and image contrast. Traditionally, many PEEMs were installed at synchrotron light sources to access intense and tunable soft X-rays. More recently, the maturation of solid-state lasers has opened a new avenue for laboratory-based PEEMs using laser-based UV light at lower photon energies. Here, we report on the characteristics of a laser-based UV light source that was recently integrated with a PEEM instrument. The system consists of a high repetition rate, tunable wavelength laser coupled to a harmonics generation module, which generates deep-UV radiation from 192 nm to 210 nm. We comment on the spectral characteristics and overall laser system stability, as well as on the effects of space charge within the PEEM microscope at high UV laser fluxes. Further, we show an example of imaging on gallium nitride, where the higher UV photon energy and flux of the laser provides considerably improved image quality, compared to a conventional light source. These results demonstrate the capabilities of laser-based UV light sources for advancing laboratory-based PEEMs.
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Affiliation(s)
- Andrew J Winchester
- Nanoscale Device and Characterization Division, National Institute of Standards and Technology, Gaithersburg, MD, United States
| | - Travis J Anderson
- Electronics Science and Technology Division, U.S. Naval Research Laboratory, Washington, DC, United States
| | - Jennifer K Hite
- Electronics Science and Technology Division, U.S. Naval Research Laboratory, Washington, DC, United States
| | - Randolph E Elmquist
- Quantum Measurement Division, National Institute of Standards and Technology, Gaithersburg, MD, United States
| | - Sujitra Pookpanratana
- Nanoscale Device and Characterization Division, National Institute of Standards and Technology, Gaithersburg, MD, United States.
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3
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Macpherson S, Doherty TAS, Winchester AJ, Kosar S, Johnstone DN, Chiang YH, Galkowski K, Anaya M, Frohna K, Iqbal AN, Nagane S, Roose B, Andaji-Garmaroudi Z, Orr KWP, Parker JE, Midgley PA, Dani KM, Stranks SD. Local Nanoscale Phase Impurities are Degradation Sites in Halide Perovskites. Nature 2022; 607:294-300. [PMID: 35609624 DOI: 10.1038/s41586-022-04872-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 05/13/2022] [Indexed: 11/09/2022]
Abstract
Understanding the nanoscopic chemical and structural changes that drive instabilities in emerging energy materials is essential for mitigating device degradation. The power conversion efficiency of halide perovskite photovoltaic devices has reached 25.7% in single junction and 29.8% in tandem perovskite/silicon cells1,2, yet retaining such performance under continuous operation has remained elusive3. Here, we develop a multimodal microscopy toolkit to reveal that in leading formamidinium-rich perovskite absorbers, nanoscale phase impurities including hexagonal polytype and lead iodide inclusions are not only traps for photo-excited carriers which themselves reduce performance4,5, but via the same trapping process are sites at which photochemical degradation of the absorber layer is seeded. We visualise illumination-induced structural changes at phase impurities associated with trap clusters, revealing that even trace amounts of these phases, otherwise undetected with bulk measurements, compromise device longevity. The type and distribution of these unwanted phase inclusions depends on film composition and processing, with the presence of polytypes being most detrimental for film photo-stability. Importantly, we reveal that performance losses and intrinsic degradation processes can both be mitigated by modulating these defective phase impurities, and demonstrate that this requires careful tuning of local structural and chemical properties. This multimodal workflow to correlate the nanoscopic landscape of beam sensitive energy materials will be applicable to a wide range of semiconductors for which a local picture of performance and operational stability has yet to be established.
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Affiliation(s)
- Stuart Macpherson
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | - Tiarnan A S Doherty
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, UK.,Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Andrew J Winchester
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan
| | - Sofiia Kosar
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan
| | - Duncan N Johnstone
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, UK
| | - Yu-Hsien Chiang
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | - Krzystof Galkowski
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, UK.,Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Toruń, Poland
| | - Miguel Anaya
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, UK.,Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Kyle Frohna
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | - Affan N Iqbal
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, UK.,Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Satyawan Nagane
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Bart Roose
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | | | - Kieran W P Orr
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, UK.,Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Julia E Parker
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Paul A Midgley
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, UK
| | - Keshav M Dani
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan.
| | - Samuel D Stranks
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, UK. .,Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK.
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4
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Towards DCS in the UV Spectral Range for Remote Sensing of Atmospheric Trace Gases. REMOTE SENSING 2020. [DOI: 10.3390/rs12203444] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The development of increasingly sensitive and robust instruments and new methodologies are essential to improve our understanding of the Earth’s climate and air pollution. In this context, Dual-Comb spectroscopy (DCS) has been successfully demonstrated as a remote laser-based instrument to probe infrared absorbing species such as greenhouse gases. We present here a study of the sensitivity of Dual-Comb spectroscopy to remotely monitor atmospheric gases focusing on molecules that absorb in the ultraviolet domain, where the most reactive molecules of the atmosphere (OH, HONO, BrO...) have their highest absorption cross-sections. We assess the achievable signal-to-noise ratio (SNR) and the corresponding minimum absorption sensitivity of DCS in the ultraviolet range. We propose a potential light source for remote sensing UV-DCS and discuss the degree of immunity of UV-DCS to atmospheric turbulences. We show that the characteristics of the currently available UV sources are compatible with the unambiguous identification of UV absorbing gases by UV-DCS.
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5
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Jain A, Parajuli P, Wang Y, Kulatilaka WD. Hydroxyl radical planar laser-induced fluorescence imaging in flames using frequency-tripled femtosecond laser pulses. OPTICS LETTERS 2020; 45:4690-4693. [PMID: 32870833 DOI: 10.1364/ol.400930] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 07/13/2020] [Indexed: 06/11/2023]
Abstract
Ultra-short optical pulses in the ultraviolet (UV) region are of significant interest for combustion and reacting flow diagnostics, as most important chemical species have electronic resonance transitions in the UV region. Optical parametric amplifiers are typically used for frequency conversion of femtosecond (fs) pulses from near-IR to UV; however, their implementation for practical imaging applications is limited because of the low conversion efficiency and extreme sensitivity to ambient conditions. In this work, we report the implementation of direct-frequency-tripled, fs laser pulses from a tunable amplified laser system for high-resolution imaging of hydroxyl (OH) radical in flames. The fundamental laser output near 850 nm is frequency tripled to obtain approximately 283.3-nm UV radiation. OH planar laser-induced fluorescence (PLIF) imaging at 1 kHz is demonstrated in turbulent flames with image sheet heights in excess of 45 mm and a signal-to-noise ratio better than 25. These results represent over 3× increase in the imaging dimensionality compared to traditional OPA-based systems. Additionally, the third-harmonic generation apparatus is compact, robust, and easy to operate while providing near-Gaussian beam profiles. Simple power scaling suggests another factor of 3 or more increase in sheet height can be achieved for kilohertz-rate practical combustion diagnostics applications.
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Jeong TM, Bulanov SV, Sasorov PV, Bulanov SS, Koga JK, Korn G. 4π-spherically focused electromagnetic wave: diffraction optics approach and high-power limits. OPTICS EXPRESS 2020; 28:13991-14006. [PMID: 32403863 DOI: 10.1364/oe.387654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 02/22/2020] [Indexed: 06/11/2023]
Abstract
The focused field and its intensity distribution achieved by the 4π-spherical focusing scheme are investigated within the framework of diffraction optics. Generalized mathematical formulas describing the spatial distributions of the focused electric and magnetic fields are derived for the transverse magnetic and transverse electric mode electromagnetic waves with and without the orbital angular momentum attribute. The mathematical formula obtained shows no singularity in the field in the focal region and satisfies the finite field strength and electromagnetic energy conditions. The 4π-spherical focusing of the transverse magnetic mode electromagnetic wave provides the highest field strength at the focus and the peak intensity reaches 1026 W/cm2 for the laser power of 100 PW at 800 nm wavelength. As an example of using the mathematical formula, the electron-positron pair production via the Schwinger mechanism is analyzed and compared with previous results.
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Performance-limiting nanoscale trap clusters at grain junctions in halide perovskites. Nature 2020; 580:360-366. [PMID: 32296189 DOI: 10.1038/s41586-020-2184-1] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 02/17/2020] [Indexed: 11/08/2022]
Abstract
Halide perovskite materials have promising performance characteristics for low-cost optoelectronic applications. Photovoltaic devices fabricated from perovskite absorbers have reached power conversion efficiencies above 25 per cent in single-junction devices and 28 per cent in tandem devices1,2. This strong performance (albeit below the practical limits of about 30 per cent and 35 per cent, respectively3) is surprising in thin films processed from solution at low-temperature, a method that generally produces abundant crystalline defects4. Although point defects often induce only shallow electronic states in the perovskite bandgap that do not affect performance5, perovskite devices still have many states deep within the bandgap that trap charge carriers and cause them to recombine non-radiatively. These deep trap states thus induce local variations in photoluminescence and limit the device performance6. The origin and distribution of these trap states are unknown, but they have been associated with light-induced halide segregation in mixed-halide perovskite compositions7 and with local strain8, both of which make devices less stable9. Here we use photoemission electron microscopy to image the trap distribution in state-of-the-art halide perovskite films. Instead of a relatively uniform distribution within regions of poor photoluminescence efficiency, we observe discrete, nanoscale trap clusters. By correlating microscopy measurements with scanning electron analytical techniques, we find that these trap clusters appear at the interfaces between crystallographically and compositionally distinct entities. Finally, by generating time-resolved photoemission sequences of the photo-excited carrier trapping process10,11, we reveal a hole-trapping character with the kinetics limited by diffusion of holes to the local trap clusters. Our approach shows that managing structure and composition on the nanoscale will be essential for optimal performance of halide perovskite devices.
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8
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Full 3D modelling of pulse propagation enables efficient nonlinear frequency conversion with low energy laser pulses in a single-element tripler. Sci Rep 2017; 7:42889. [PMID: 28225007 PMCID: PMC5320497 DOI: 10.1038/srep42889] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 01/16/2017] [Indexed: 11/12/2022] Open
Abstract
Although new optical materials continue to open up access to more and more wavelength bands where femtosecond laser pulses can be generated, light frequency conversion techniques are still indispensable in filling the gaps on the ultrafast spectral scale. With high repetition rate, low pulse energy laser sources (oscillators) tight focusing is necessary for a robust wave mixing and the efficiency of broadband nonlinear conversion is limited by diffraction as well as spatial and temporal walk-off. Here we demonstrate a miniature third harmonic generator (tripler) with conversion efficiency exceeding 30%, producing 246 fs UV pulses via cascaded second order processes within a single laser beam focus. Designing this highly efficient and ultra compact frequency converter was made possible by full 3-dimentional modelling of propagation of tightly focused, broadband light fields in nonlinear and birefringent media.
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9
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Faure J, Mauchain J, Papalazarou E, Yan W, Pinon J, Marsi M, Perfetti L. Full characterization and optimization of a femtosecond ultraviolet laser source for time and angle-resolved photoemission on solid surfaces. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2012; 83:043109. [PMID: 22559517 DOI: 10.1063/1.3700190] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A novel experimental apparatus for time and angle-resolved photoemission on solid surfaces is presented. A 6.28 eV laser source operating at 250 kHz repetition rate is obtained by frequency mixing in nonlinear beta barium borate crystals. This UV light source has a high photon flux of 10(13) photons/s with relatively low number of photons/pulse so that Fermi surface mapping over a wide region of the Brillouin zone is possible while mitigating space charge effects. The UV source has been fully characterized spatially, spectrally, and temporally. Its potential for time and angle-resolved photoemission is demonstrated through Fermi surface mapping and photoexcited electron dynamics in Bismuth. True femtosecond time resolution <65 fs is obtained while the energy resolution of 70 meV appears to be mainly limited by the laser bandwidth.
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Affiliation(s)
- J Faure
- Laboratoire d'Optique Appliquée, ENSTA-CNRS-Ecole Polytechnique, UMR 7639, 91761 Palaiseau, France
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Peters E, Diddams SA, Fendel P, Reinhardt S, Hänsch TW, Udem T. A deep-UV optical frequency comb at 205 nm. OPTICS EXPRESS 2009; 17:9183-9190. [PMID: 19466167 DOI: 10.1364/oe.17.009183] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
By frequency quadrupling a picosecond pulse train from a Ti:sapphire laser at 820 nm we generate a frequency comb at 205 nm with nearly bandwidth-limited pulses. The nonlinear frequency conversion is accomplished by two successive frequency doubling stages that take place in resonant cavities that are matched to the pulse repetition rate of 82 MHz. This allows for an overall efficiency of 4.5 % and produces an output power of up to 70 mW for a few minutes and 25 mW with continuous operation for hours. Such a deep UV frequency comb may be employed for direct frequency comb spectroscopy in cases where it is less efficient to convert to these short wavelengths with continuous wave lasers.
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Affiliation(s)
- E Peters
- Max Planck Institute of Quantum Optics, Hans-Kopfermann-Str. 1, D-85748 Garching, Germany.
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Dubietis A, Tamosauskas G, Varanavi Ius A, Valiulis G. Two-Photon Absorbing Properties of Ultraviolet Phase-Matchable Crystals at 264 and 211 nm. APPLIED OPTICS 2000; 39:2437-2440. [PMID: 18345157 DOI: 10.1364/ao.39.002437] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We investigated the intensity-dependent loss properties of nonlinear crystals by using subpicosecond laser pulses at 264 and 211 nm. Two-photon absorption coefficients for potassium dihydrogen phosphate, beta-barium borate, and lithium triborate crystals were obtained from the intensity-dependent transmission measurements.
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