• High Power Laser Science and Engineering
  • Vol. 9, Issue 4, 04000e62 (2021)
Hiromitsu Kiriyama1、*, Yasuhiro Miyasaka1, Akira Kon1, Mamiko Nishiuchi1, Akito Sagisaka1, Hajime Sasao2, Alexander S. Pirozhkov1, Yuji Fukuda1, Koichi Ogura1, Kotaro Kondo1, Nicholas P. Dover1, and Masaki Kando1
Author Affiliations
  • 1Kansai Photon Science Institute, National Institutes for Quantum Science and Technology (QST), Kizugawa619-0215, Japan
  • 2Naka Fusion Institute, National Institutes for Quantum Science and Technology (QST), Naka311-0193, Japan
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    Abstract

    We have experimentally improved the temporal contrast of the petawatt J-KAREN-P laser facility. We have investigated how the generation of pre-pulses by post-pulses changes due to the temporal overlap between the stretched pulse and the post-pulse in a chirped-pulse amplification system. We have shown that the time at which the pre-pulse is generated by the post-pulse and its shape are related to the time difference between the stretched main pulse and the post-pulse. With this investigation, we have found and identified the origins of the pre-pulses and have demonstrated the removal of most pre-pulses by eliminating the post-pulse with wedged optics. We have also demonstrated the impact of stretcher optics on the picosecond pedestal. We have realized orders of magnitude enhancement of the pedestal by improving the optical quality of a key component in the stretcher.

    1. Introduction

    With the remarkable progress in chirped-pulse amplification (CPA) technology and Ti:sapphire laser media, femtosecond lasers with very high peak powers of 1–10 petawatt (PW)[16] have been developed around the world and extremely high intensities of 1022–1023 W/cm2[79] are now available. Owing to the limitation of the available size and transverse parasitic oscillation in the Ti:sapphire gain media, femtosecond lasers based on optical parametric chirped-pulse amplifiers (OPCPAs) with a peak power of order 100 PW have been designed and are under construction[10,11]. The laser intensity will possibly exceed 1023 W/cm2 in the near future. With the development of ultra-high-intensity femtosecond lasers, the investigations of electron acceleration, ion acceleration, X-/γ-ray generation and astrophysical systems are being actively pursued.

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    Hiromitsu Kiriyama, Yasuhiro Miyasaka, Akira Kon, Mamiko Nishiuchi, Akito Sagisaka, Hajime Sasao, Alexander S. Pirozhkov, Yuji Fukuda, Koichi Ogura, Kotaro Kondo, Nicholas P. Dover, Masaki Kando. Enhancement of pre-pulse and picosecond pedestal contrast of the petawatt J-KAREN-P laser[J]. High Power Laser Science and Engineering, 2021, 9(4): 04000e62
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    Category: Research Articles
    Received: Sep. 7, 2021
    Accepted: Oct. 28, 2021
    Posted: Nov. 2, 2021
    Published Online: Nov. 23, 2021
    The Author Email: Hiromitsu Kiriyama (kiriyama.hiromitsu@qst.go.jp)