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Title: High-efficiency, large-aperture fifth-harmonic: Generation of 211-nm pulses in ammonium dihydrogen phosphate crystals for fusion diagnostics

Abstract

High-energy ultraviolet (UV) sources are required to probe hot dense plasmas from fusion experiments by using Thomson scattering resulting from the lower self-generated background from the plasma in the 180 to 230-nm spectral region. Although recently we demonstrated efficient, joule-class fifth harmonic conversion of 1053-nm pulses using a cesium lithium borate (CLBO) crystal, larger crystals are necessary for increased UV energy. This paper presents an alternative approach for fifth-harmonic generation of a large-aperture neodymium laser using ammonium dihydrogen phosphate (ADP). An Nd:YLF laser was optimized to produce square pulses with a flattop, square beam profile (1053 nm, 1 to 2.8 ns, 12 x 12 mm, ≤1.5 J, ≤5 Hz). Noncritical phase matching in ADP suitable for sum–frequency mixing the fourth harmonic with residual fundamental light was achieved by cooling the crystal (65 x 65 x 10 mm) in a two-chamber cryostat to 200 K. The crystal chamber used helium (1 atm) as the thermally conductive medium between the crystal and the crystal chamber, which in turn was surrounded by a high-vacuum chamber that contained a liquid nitrogen reservoir to cool the crystal chamber. Temperature variation of 0.4 K across the crystal aperture was obtained using two 50-W heaters with activemore » feedback. The total conversion efficiency from the fundamental to the fifth harmonic, including surface losses and absorption, was 26%.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Univ. of Rochester, NY (United States). Lab. for Laser Energetics
Publication Date:
Research Org.:
Univ. of Rochester, Rochester, NY (United States). Lab. for Laser Energetics
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1505789
Report Number(s):
2018-204, 1484
2018-204, 1484, 2443
Grant/Contract Number:  
NA0003856
Resource Type:
Accepted Manuscript
Journal Name:
Proc. SPIE
Additional Journal Information:
Journal Volume: 10898; Conference: Photonics West, San Francisco, CA, 2-7 February 2019
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Fifth harmonic generation; ammonium dihydrogen phosphate; Nd:YLF laser; two-chamber cryostat; ultraviolet; noncritical phase matching

Citation Formats

Begishev, Ildar, Romanofsky, Mark, Carey, Sean, Chapman, Raymond, Brent, Gregory, Shoup, Milton, Zuegel, Jonathan, Bromage, Jake, Haefner, Constantin L., and Awwal, Abdul A. High-efficiency, large-aperture fifth-harmonic: Generation of 211-nm pulses in ammonium dihydrogen phosphate crystals for fusion diagnostics. United States: N. p., 2019. Web. doi:10.1117/12.2506557.
Begishev, Ildar, Romanofsky, Mark, Carey, Sean, Chapman, Raymond, Brent, Gregory, Shoup, Milton, Zuegel, Jonathan, Bromage, Jake, Haefner, Constantin L., & Awwal, Abdul A. High-efficiency, large-aperture fifth-harmonic: Generation of 211-nm pulses in ammonium dihydrogen phosphate crystals for fusion diagnostics. United States. doi:10.1117/12.2506557.
Begishev, Ildar, Romanofsky, Mark, Carey, Sean, Chapman, Raymond, Brent, Gregory, Shoup, Milton, Zuegel, Jonathan, Bromage, Jake, Haefner, Constantin L., and Awwal, Abdul A. Mon . "High-efficiency, large-aperture fifth-harmonic: Generation of 211-nm pulses in ammonium dihydrogen phosphate crystals for fusion diagnostics". United States. doi:10.1117/12.2506557.
@article{osti_1505789,
title = {High-efficiency, large-aperture fifth-harmonic: Generation of 211-nm pulses in ammonium dihydrogen phosphate crystals for fusion diagnostics},
author = {Begishev, Ildar and Romanofsky, Mark and Carey, Sean and Chapman, Raymond and Brent, Gregory and Shoup, Milton and Zuegel, Jonathan and Bromage, Jake and Haefner, Constantin L. and Awwal, Abdul A.},
abstractNote = {High-energy ultraviolet (UV) sources are required to probe hot dense plasmas from fusion experiments by using Thomson scattering resulting from the lower self-generated background from the plasma in the 180 to 230-nm spectral region. Although recently we demonstrated efficient, joule-class fifth harmonic conversion of 1053-nm pulses using a cesium lithium borate (CLBO) crystal, larger crystals are necessary for increased UV energy. This paper presents an alternative approach for fifth-harmonic generation of a large-aperture neodymium laser using ammonium dihydrogen phosphate (ADP). An Nd:YLF laser was optimized to produce square pulses with a flattop, square beam profile (1053 nm, 1 to 2.8 ns, 12 x 12 mm, ≤1.5 J, ≤5 Hz). Noncritical phase matching in ADP suitable for sum–frequency mixing the fourth harmonic with residual fundamental light was achieved by cooling the crystal (65 x 65 x 10 mm) in a two-chamber cryostat to 200 K. The crystal chamber used helium (1 atm) as the thermally conductive medium between the crystal and the crystal chamber, which in turn was surrounded by a high-vacuum chamber that contained a liquid nitrogen reservoir to cool the crystal chamber. Temperature variation of 0.4 K across the crystal aperture was obtained using two 50-W heaters with active feedback. The total conversion efficiency from the fundamental to the fifth harmonic, including surface losses and absorption, was 26%.},
doi = {10.1117/12.2506557},
journal = {Proc. SPIE},
number = ,
volume = 10898,
place = {United States},
year = {2019},
month = {3}
}

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This content will become publicly available on March 4, 2020
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