Abstract
We briefly review recent results on photoemission spectroscopy based on the deep and vacuum ultraviolet diode pumped solid-state lasers which we have developed. Cascaded second harmonic generation with the nonlinear crystal KBe2BO3F2 (KBBF) is used to generate deep ultraviolet and vacuum ultraviolet laser radiation, which complements traditional incoherent light sources such as gas discharge lamps and synchrotron radiation, and has greatly improved resolution with respect to energy, momentum, and spin of photoemission spectroscopy. Many new functions have been developed with the advantages of high photon energy, narrow linewidth, high photon flux density, and so on. These have led to the observation of various new phenomena and the amassment of new data in the fields of high temperature superconductivity, topological electronics, Fermi semi-metals, and so forth. These laser systems have revived the field of photoemission spectroscopy and provided a new platform in this frontier research field.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Ali MN, Xiong J, Flynn S, et al., 2014. Large, non-saturating magnetoresistance in WTe2. Nature, 514(7521): 205–208. https://doi.org/10.1038/nature13763
Beamson G, Briggs D, Davies SF, et al., 1990. Performance and application of the Scienta ESCA300 spectrometer. Surf Interf Anal, 15(9): 541–549. https://doi.org/10.1002/sia.740150908
Bogdanov PV, Lanzara A, Kellar SA, et al., 2000. Evidence for an energy scale for quasiparticle dispersion in Bi2Sr2CaCu2O8. Phys Rev Lett, 85(12): 2581–2584. https://doi.org/10.1103/PhysRevLett.85.2581
Bok JM, Yun JH, Choi HY, et al., 2010. Momentum dependence of the single-particle self-energy and fluctuation spectrum of slightly underdoped Bi2Sr2CaCu2O8+d from high-resolution laser angle-resolved photoemission. Phys Rev B, 81(17):174516. https://doi.org/10.1103/PhysRevB.81.174516
Chen CT, 2004. Recent advances in deep and vacuum-UV harmonic generation with KBBF crystal. Opt Mater, 26(4): 425–429. https://doi.org/10.1016/j.optmat.2004.02.007
Chen CT, Xu ZY, Deng DQ, et al., 1996. The vacuum ultraviolet phase-matching characteristics of nonlinear optical KBe2BO3F2 crystal. Appl Phys Lett, 68(21): 2930–2932. https://doi.org/10.1063/1.116358
Chen CT, Xu ZY, Lü JH, et al., 2004. Variable-frequency laser coupler with non-linear optical crystal. Chinese Patent No. CN1172411C (in Chinese).
Chen CT, Kanai T, Wang XY, et al., 2008. High-average-power light source below 200 nm from a KBe2BO3F2 prismcoupled device. Opt Lett, 33(3): 282–284. https://doi.org/10.1364/OL.33.000282
Chen CT, Wang GL, Wang XY, et al., 2009. Deep-UV nonlinear optical crystal KBe2BO3F2—discovery, growth, optical properties and applications. Appl Phys B, 97(1): 9–25. https://doi.org/10.1007/s00340-009-3554-4
Couprie ME, 2014. New generation of light sources: present and future. J Electron Spectrosc Relat Phenom, 196:3–13. https://doi.org/10.1016/j.elspec.2013.12.007
Cyranoski D, 2009. Materials science: China’s crystal cache. Nature, 457(7232): 953–955. https://doi.org/10.1038/457953a
Dagotto E, 2005. Complexity in strongly correlated electronic systems. Science, 309(5732): 257–262. https://doi.org/10.1126/science.1107559
Dai SB, Zong N, Yang F, et al., 2015. 167.75-nm vacuum-ultraviolet ps laser by eighth-harmonic generation of a 1342-nm Nd:YVO4 amplifier in KBBF. Opt Lett, 40(14): 3268–3271. https://doi.org/10.1364/OL.40.003268
Dai SB, Chen M, Zhang SJ, et al., 2016. 2.14 mW deep-ultraviolet laser at 165 nm by eighth-harmonic generation of a 1319 nm Nd:YAG laser in KBBF. Laser Phys Lett, 13(3):035401. https://doi.org/10.1088/1612-2011/13/3/035401
Damascelli A, Hussain Z, Shen ZX, 2003. Angle-resolved photoemission studies of the cuprate superconductors. Rev Mod Phys, 75(2): 473–541. https://doi.org/10.1103/RevModPhys.75.473
Einstein A, 1905. Generation and conversion of light with regard to a heuristic point of view. Ann Phys, 322(6): 132–148. https://doi.org/10.1002/andp.19053220607
Fujii T, Kumagai H, Midorikawa K, et al., 2000. Development of a high-power deep-ultraviolet continuous-wave coherent light source for laser cooling of silicon atoms. Opt Lett, 25(19): 1457–1459. https://doi.org/10.1364/OL.25.001457
Graf J, Hellmann S, Jozwiak C, et al., 2010. Vacuum space charge effect in laser-based solid-state photoemission spectroscopy. J Appl Phys, 107(1):014912. https://doi.org/10.1063/1.3273487
Greber T, Raetzo O, Kreutz TJ, et al., 1997. A photoelectron spectrometer for k-space mapping above the Fermi level. Rev Sci Instrum, 68(12): 4549–4554. https://doi.org/10.1063/1.1148429
Grüner F, Becker S, Schramm U, et al., 2007. Design considerations for table-top, laser-based VUV and X-ray free electron lasers. Appl Phys B, 86(3): 431–435. https://doi.org/10.1007/s00340-006-2565-7
Haight R, Peale DR, 1994. Tunable photoemission with harmonics of subpicosecond lasers. Rev Sci Instrum, 65(6): 1853–1857. https://doi.org/10.1063/1.1144834
Haight R, Silberman JA, Lilie MI, 1988. Novel system for picosecond photoemission spectroscopy. Rev Sci Instrum, 59(9): 1941–1946. https://doi.org/10.1063/1.1140055
Hertz H, 1887. Ueber einen Einfluss des ultravioletten Lichtes auf die electrische Entladung. Ann Phys, 267(8): 983–1000 (in German). https://doi.org/10.1002/andp.18872670827
Huang LN, McCormick TM, Ochi M, et al., 2016. Spectro-scopic evidence for a type II Weyl semimetallic state in M o Te 2. Nat Mater, 15(11): 1155–1160. https://doi.org/10.1038/nmat4685
Hüfner S, 1995. Photoelectron Spectroscopy: Principles and Applications. Springer-Verlag Berlin Heidelberg.
Hüfner S, 2003. Photoelectron Spectroscopy: Principles and Applications (3rd Ed.). Springer-Verlag Berlin Heidelberg.
Jiang R, Mou DX, Wu Y, et al., 2014. Tunable vacuum ultraviolet laser based spectrometer for angle resolved photoemission spectroscopy. Rev Sci Instrum, 85(3):033902. https://doi.org/10.1063/1.4867517
Johnson PD, Valla T, Fedorov AV, et al., 2001. Doping and temperature dependence of the mass enhancement observed in the cuprate Bi2Sr2CaCu2O8+δ. Phys Rev Lett, 87(17):177007. https://doi.org/10.1103/PhysRevLett.87.177007
Kaminski A, Randeria M, Campuzano JC, et al., 2001. Renormalization of spectral line shape and dispersion below T c in Bi2Sr2CaCu2O8+δ. Phys Rev Lett, 86(6): 1070–1073. https://doi.org/10.1103/PhysRevLett.86.1070
Kanai T, Wang XY, Adachi S, et al., 2009. Watt-level tunable deep ultraviolet light source by a KBBF prism-coupled device. Opt Expr, 17(10): 8696–8703. https://doi.org/10.1364/OE.17.008696
Karlsson HS, Chiaia G, Karlsson UO, 1996. A system for time-and angle-resolved photoelectron spectroscopy based on an amplified femtosecond titanium:sapphire laser system. Rev Sci Instrum, 67(10): 3610–3615. https://doi.org/10.1063/1.1147067
Kiss T, Kanetaka F, Yokoya T, et al., 2005. Photoemission spectroscopic evidence of gap anisotropy in an f-electron superconductor. Phys Rev Lett, 94(5):057001. https://doi.org/10.1103/PhysRevLett.94.057001
Kiss T, Shimojima T, Ishizaka K, et al., 2008. A versatile system for ultrahigh resolution, low temperature, and polarization dependent laser-angle-resolved photoemission spectroscopy. Rev Sci Instrum, 79(2):023106. https://doi.org/10.1063/1.2839010
Koch P, Bartschke J, L’huillier JA, 2016. High-power actively Q-switched single-mode 1342 nm Nd:YVO4 ring laser, injection-locked by a CW single-frequency microchip laser. Opt Expr, 23(24): 31357–31366. https://doi.org/10.1364/OE.23.031357
Koralek JD, Douglas JF, Plumb NC, et al., 2006. Laser based angle-resolved photoemission, the sudden approximation, and quasiparticle-like spectral peaks in Bi2Sr2CaCu2O8+δ. Phys Rev Lett, 96(1):017005. https://doi.org/10.1103/PhysRevLett.96.017005
Koralek JD, Douglas JF, Plumb NC, et al., 2007. Experimental setup for low-energy laser-based angle resolved photoemission spectroscopy. Rev Sci Instrum, 78(5):053905. https://doi.org/10.1063/1.2722413
Lanzara A, Bogdanov PV, Zhou XJ, et al., 2001. Evidence for ubiquitous strong electron–phonon coupling in high-temperature superconductors. Nature, 412(6846): 510–514. https://doi.org/10.1038/35087518
Li CM, Zhou Y, Zong N, et al., 2009. Sixth harmonic generation of 1064-nm laser in KBBF prism coupling devices under two kinds of gas conditions. Chin Opt Lett, 7(7): 621–623.
Li FQ, Zong N, Zhang FF, et al., 2012. Investigation of third-order optical nonlinearity in KBe2BO3F2 crystal by Z-scan. Appl Phys B, 108(2): 301–305. https://doi.org/10.1007/s00340-012-4985-x
Liu GD, Wang GL, Zhu Y, et al., 2008. Development of a vacuum ultraviolet laser-based angle-resolved photoemission system with a superhigh energy resolution better than 1 meV. Rev Sci Instrum, 79(2):023105. https://doi.org/10.1063/1.2835901
Lv JH, Wang GL, Xu ZY, et al., 2001. High-efficiency fourth-harmonic generation of KBBF crystal. Opt Commun, 200(1–6):415–418. https://doi.org/10.1016/S0030-4018(01)01654-6
Mai ZH, 2013. Synchrotron Radiation Source and Its Application. Science Press, Beijing, China, p.152–620 (in Chinese).
Mårtensson N, Baltzer P, Brühwiler PA, et al., 1994. A very high resolution electron spectrometer. J Electron Spec-trosc Relat Phenom, 70(2): 117–128. https://doi.org/10.1016/0368-2048(94)02224-N
Mathias S, Miaja-Avila L, Murnane MM, et al., 2007. Angle-resolved photoemission spectroscopy with a femtosecond high harmonic light source using a two-dimensional imaging electron analyzer. Rev Sci Instrum, 78(8):083105. https://doi.org/10.1063/1.2773783
Nagashima K, Liu LQ, 2001. Phase-matching properties of nonlinear crystals in deep ultraviolet. Opt Laser Technol, 33(8): 611–615. https://doi.org/10.1016/s0030-3992(01)00084-6
Nakazato T, Ito I, Kobayashi Y, et al., 2016. Phase-matched frequency conversion below 150 nm in KBe2BO3F2. Opt Expr, 24(15): 17149–17158. https://doi.org/10.1364/OE.24.017149
Nessler W, Ogawa S, Nagano H, et al., 1998. Femtosecond time-resolved study of the energy and temperature dependence of hot-electron lifetimes in Bi2Sr2CaCu2O8+δ. Phys Rev Lett, 81(20): 4480–4483. https://doi.org/10.1103/PhysRevLett.81.4480
Nomura Y, Ito Y, Ozawa A, et al., 2011. Coherent quasi-cw 153 nm light source at 33 MHz repetition rate. Opt Lett, 36(10): 1758–1760. https://doi.org/10.1364/OL.36.001758
Nordling C, Sokolowski E, Siegbahn K, 1957. Precision method for obtaining absolute values of atomic binding energies. Phys Rev, 105(5): 1676–1677. https://doi.org/10.1103/PhysRev.105.1676
Passlack S, Mathias S, Andreyev O, et al., 2006. Space charge effects in photoemission with a low repetition, high intensity femtosecond laser source. J Appl Phys, 100(2): 024912. https://doi.org/10.1063/1.2217985
Peng QJ, Zong N, Zhang SJ, et al., 2018. DUV/VUV all-solid-state lasers: twenty years of progress and the future. IEEE J Sel Top Quant Electron, 24(5):1602312. https://doi.org/10.1109/JSTQE.2018.2829665
Perfetti L, Loukakos PA, Lisowski M, et al., 2006. Time evolution of the electronic structure of 1T-TaS 2 through the insulator-metal transition. Phys Rev Lett, 97(6):067402. https://doi.org/10.1103/PhysRevLett.97.067402
Petersen JC, Kaiser S, Dean N, et al., 2011. Clocking the melting transition of charge and lattice order in 1T-Ta S 2 with ultrafast extreme-ultraviolet angle-resolved photoemission spectroscopy. Phys Rev Lett, 107(17):177402. https://doi.org/10.1103/PhysRevLett.107.177402
Petrov V, Rotermund F, Noack F, 1998a. Generation of femtosecond pulses down to 166 nm by sum-frequency mixing in KB5O8.4H2O. Electron Lett, 34(18): 1748–1750. https://doi.org/10.1049/el:19981223
Petrov V, Rotermund F, Noack F, et al., 1998b. Vacuum ultraviolet application of Li2B4O7 crystals: generation of 100 fs pulses down to 170 nm. J Appl Phys, 84(11): 5887–5892. https://doi.org/10.1063/1.368904
Reber TJ, Plumb NC, Waugh JA, et al., 2014. Effects, determination, and correction of count rate nonlinearity in multi-channel analog electron detectors. Rev Sci Instrum, 85(4):043907. https://doi.org/10.1063/1.4870283
Rohwer T, Hellmann S, Wiesenmayer M, et al., 2011. Collapse of long-range charge order tracked by time-resolved photoemission at high momenta. Nature, 471(7339): 490–493. https://doi.org/10.1038/nature09829
Shi JR, Tang SJ, Wu B, et al., 2004. Direct extraction of the Eliashberg function for electron-phonon coupling: a case study of Be(1010). Phys Rev Lett, 92(18):186401. https://doi.org/10.1103/PhysRevLett.92.186401
Shimojima T, Okazaki K, Shin S, 2015. Low-temperature and high-energy-resolution laser photoemission spectroscopy. J Phys Soc Jpn, 84(7):072001. https://doi.org/10.7566/JPSJ.84.072001
Smallwood CL, Zhang WT, Miller TL, et al., 2014. Time- and momentum-resolved gap dynamics in Bi2Sr2CaCu2O8+δ. Phys Rev B, 89(11):115126. https://doi.org/10.1103/PhysRevB.89.115126
Smith NV, Traum MM, 1973. Angular dependence of photoemission from the (110) face of GaAs. Phys Rev Lett, 31(20): 1247–1250. https://doi.org/10.1103/PhysRevLett.31.1247
Smith NV, Traum MM, di Salvo FJ, 1974. Mapping energy bands in layer compounds from the angular dependence of ultraviolet photoemission. Sol State Commun, 15(2): 211–214. https://doi.org/10.1016/0038-1098(74)90743-1
Sobota JA, Yang SL, Kemper AF, et al., 2013. Direct optical coupling to an unoccupied Dirac surface state in the top-ological insulator Bi2Se3. Phys Rev Lett, 111(13):136802. https://doi.org/10.1103/PhysRevLett.111.136802
Soluyanov AA, Gresch D, Wang ZJ, et al., 2015. Type-II Weyl semimetals. Nature, 527(7579): 495–498. https://doi.org/10.1038/nature15768
Taniuchi T, Kotani Y, Shin S, 2015. Ultrahigh-spatial-resolution chemical and magnetic imaging by laser-based photoemission electron microscopy. Rev Sci Instrum, 86(2):023701. https://doi.org/10.1063/1.4906755
Trabs P, Noack F, Aleksandrovsky AS, et al., 2016. Generation of coherent radiation in the vacuum ultraviolet using randomly quasi-phase-matched strontium tetraborate. Opt Lett, 41(3): 618–621. https://doi.org/10.1364/OL.41.000618
Wang CL, Zhang Y, Huang JW, et al., 2017. Evidence of electron-hole imbalance in WTe2 from high-resolution angle-resolved photoemission spectroscopy. Chin Phys Lett, 34(9):097305. https://doi.org/10.1088/0256-307X/34/9/097305
Wang GL, Wang XY, Zhou Y, et al., 2008a. 12.95 mW sixth harmonic generation with KBe2BO3F2 crystal. Appl Phys B, 91(1): 95–97. https://doi.org/10.1007/s00340-007-2922-1
Wang GL, Wang XY, Zhou Y, et al., 2008b. High-efficiency frequency conversion in deep ultraviolet with a KBe2BO3F2 prism-coupled device. Appl Opt, 47(3): 486–488. https://doi.org/10.1364/AO.47.000486
Wang YH, Steinberg H, Jarillo-Herrero P, et al., 2013. Observation of Floquet-Bloch states on the surface of a topo-logical insulator. Science, 342(6157): 453–457. https://doi.org/10.1126/science.1239834
Wang ZM, Zhang JY, Yang F, et al., 2009. Stable operation of 4 mW nanoseconds radiation at 177.3 nm by second harmonic generation in KBe2BO3F2 crystals. Opt Expr, 17(22): 20021–20032. https://doi.org/10.1364/OE.17.020021
Won R, 2014. Two-dimensional materials: laser Q-switching. Nat Photon, 8(6):422. https://doi.org/10.1038/nphoton.2014.123
Wu Y, Mou DX, Jo NH, et al., 2016. Observation of Fermi arcs in the type-II Weyl semimetal candidate WTe2. Phys Rev B, 94(12):121113. https://doi.org/10.1103/PhysRevB.94.121113
Xie ZJ, He SL, Chen CY, et al., 2014. Orbital-selective spin texture and its manipulation in a topological insulator. Nat Commun, 5:3382. https://doi.org/10.1038/ncomms4382
Xu B, Liu LJ, Wang XY, et al., 2015. Generation of high power 200 mW laser radiation at 177.3 nm in KBe2BO3F2 crystal. Appl Phys B, 121(4): 489–494. https://doi.org/10.1007/s00340-015-6260-4
Xu M, Ermolenkov VV, Uversky VN, et al., 2008. Hen egg white lysozyme fibrillation: a deep-UV resonance Raman spectroscopic study. J Biophoton, 1(3): 215–229. https://doi.org/10.1002/jbio.200710013
Xu Z, Zhang FF, Zhang SJ, et al., 2014a. Experimental investigation and theoretical analysis of pulse repetition rate adjustable deep ultraviolet picosecond radiation by second harmonic generation in KBe2BO3F2. Laser Phys, 24(6):065401. https://doi.org/10.1088/1054-660X/24/6/065401
Xu Z, Tu W, Yang F, et al., 2014b. Narrow linewidth 177.3-nm nanosecond laser with high efficiency and high power. IEEE Photon Technol Lett, 26(10): 980–982. https://doi.org/10.1109/LPT.2014.2311091
Xu ZY, Lü JH, Wang GL, et al., 2001. Non-linear Optical Crystal Laser Frequency Variable Grating Coupler. Chinese Patent No. CN01123553.5 (in Chinese).
Yang F, Wang Z, Zhou Y, et al., 2009. Theoretical and experimental investigations of nanosecond 177.3 nm deepultraviolet light by second harmonic generation in KBBF. Appl Phys B, 96(2–3):415–422. https://doi.org/10.1007/s00340-009-3506-z
Yang F, Wang ZM, Zhou Y, et al., 2010. 41 mW high average power picosecond 177.3 nm laser by second-harmonic generation in KBBF. Opt Commun, 283(1): 142–145. https://doi.org/10.1016/j.optcom.2009.09.051
Yang J, Yang F, Zhang JY, et al., 2013. Pulse broadening of deep ultraviolet femtosecond laser from second harmonic generation in KBe2BO3F2 crystal. Opt Commun, 288: 114–117. https://doi.org/10.1016/j.optcom.2012.09.054
Zhang FF, Yang F, Zhang SJ, et al., 2012. A polarization-adjustable picosecond deep-ultraviolet laser for spin- and angle-resolved photoemission spectroscopy. Chin Phys Lett, 29(6):064206. https://doi.org/10.1088/0256-307X/29/6/064206
Zhang FF, Yang F, Zhang SJ, et al., 2013. Picosecond widely tunable deep-ultraviolet laser for angle-resolved photoemission spectroscopy. Chin Phys B, 22(6):064212. https://doi.org/10.1088/1674-1056/22/6/064212
Zhang HJ, Wang G, Guo L, et al., 2008. 175 to 210 nm widely tunable deep-ultraviolet light generation based on KBBF crystal. Appl Phys B, 93(2–3):323–326. https://doi.org/10.1007/s00340-008-3198-9
Zhang HJ, Liu CX, Zhang SC, 2013. Spin-orbital texture in topological insulators. Phys Rev Lett, 111(6):066801. https://doi.org/10.1103/PhysRevLett.111.066801
Zhang SJ, Cui DF, Zhang FF, et al., 2014. High power all solid state VUV lasers. J Electron Spectrosc Relat Phenom, 196:20–23. https://doi.org/10.1016/j.elspec.2014.01.018
Zhang WT, Liu GD, Meng JQ, et al., 2008. High energy dispersion relations for the high temperature Bi2Sr2CaCu2O8 superconductor from laser-based angle-resolved photoemission spectroscopy. Phys Rev Lett, 101(1):017002. https://doi.org/10.1103/PhysRevLett.101.017002
Zhang WT, Smallwood CL, Jozwiak C, et al., 2013. Signatures of superconductivity and pseudogap formation in non-equilibrium nodal quasiparticles revealed by ultrafast angle-resolved photoemission. Phys Rev B, 88(24): 245132. https://doi.org/10.1103/PhysRevB.88.245132
Zhang X, Wang ZM, Wang GL, et al., 2009. Widely tunable and high-average-power fourth-harmonic generation of a Ti:sapphire laser with a KBe2BO3F2 prism-coupled device. Opt Lett, 34(9): 1342–1344. https://doi.org/10.1364/OL.34.001342
Zhang X, Wang ZM, Luo SY, et al., 2011. Widely tunable fourth harmonic generation of a Ti: sapphire laser based on RBBF crystal. Appl Phys B, 102(4): 825–830. https://doi.org/10.1007/s00340-011-4370-1
Zhang Y, Sato Y, Watanabe N, et al., 2009. Generation of quasi-continuous-wave vacuum-ultraviolet coherent light by fourth-harmonic of a Ti: sapphire laser with KBBF crystal. Opt Expr, 17(10): 8119–8124. https://doi.org/10.1364/OE.17.008119
Zhang Y, Wang CL, Yu L, et al., 2017. Electronic evidence of temperature-induced Lifshitz transition and topological nature in ZrTe5. Nat Commun, 8:15512. https://doi.org/10.1038/ncomms15512
Zhou C, Kanai T, Wang XY, et al., 2012. Generation of ultrashort 25-µJ pulses at 200 nm by dual broadband frequency doubling with a thin KBe2BO3F2 crystal. Opt Expr, 20(13): 13684–13691. https://doi.org/10.1364/OE.20.013684
Zhou XJ, Yoshida T, Lanzara A, et al., 2003. High-temperature superconductors: universal nodal Fermi velocity. Nature, 423(6938):398. https://doi.org/10.1038/423398a
Zhou XJ, He SL, Liu GD, et al., 2018. New developments in laser-based photoemission spectroscopy and its scientific applications: a key issues review. Rep Prog Phys, 81(6): 062101. https://doi.org/10.1088/1361-6633/aab0cc
Zhou Y, Wang GL, Li CM, et al., 2008. Sixth harmonic of a Nd: YVO4 laser generation in KBBF for ARPES. Chin Phys Lett, 25(3): 963–965. https://doi.org/10.1088/0256-307X/25/3/043
Author information
Authors and Affiliations
Corresponding author
Additional information
Project supported by the National Development Project for Major Scientific Research Facility (No. ZDYZ2012-2) and the National Instrumentation Program (No. 2012YQ120048)
Rights and permissions
About this article
Cite this article
Xu, Zy., Zhang, Sj., Zhou, Xj. et al. Advances in deep ultraviolet laser based high-resolution photoemission spectroscopy. Frontiers Inf Technol Electronic Eng 20, 885–913 (2019). https://doi.org/10.1631/FITEE.1800744
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1631/FITEE.1800744
Key words
- Deep and vacuum ultraviolet laser
- Second harmonic generation
- KBe2BO3F2 nonlinear crystal
- Photoelectron spectroscopy