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On target contrast ratio study for petawatt level femtosecond laser system
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Paper Abstract

To ensure a high signal to noise contrast ratio, lots of challengeable work must be done during the construction of a petawatt level laser system. In this report, we analyse the effects on the contrast ratio by the optical element manufacture errors expressed as the peak-valley value (PV value) and the PV gradient value, the chromatic aberration and group delay in system design. Using the Fourier transformation method with the random phase attached on the laser beam in frequency domain, it is proved that for manufacture errors, PV gradient value is more tolerable than that of PV value. At the terminal end of a petawatt level laser system, there exist, in pulse compressor, spectral clip, grating manufacture errors and non-uniformity of the diffraction efficiency that will affect the final SN contrast ratio of the laser system. Since the spectral clip here is soft that can benefit the promotion of the contrast ratio. But for manufacture errors of the large size grating, when PV = 1/5 wavelength, and PV differential gradient about 1/75 wavelength per centimeter. The terminal SN contrast ratio is restrained. When focused on the target, simulation for SN contrast ratio near the focal region caused by the residual distortion is taken. Calculation shows that, for a 20 microns focal spot, to maintain the 108:1 contrast ratio across the whole focal spot, residual wavefront distortion should be compensated to PV value less than 0.2 wavelength.

Paper Details

Date Published: 26 April 2019
PDF: 10 pages
Proc. SPIE 11034, Short-pulse High-energy Lasers and Ultrafast Optical Technologies, 110340H (26 April 2019); doi: 10.1117/12.2520821
Show Author Affiliations
Xinglong Xie, Shanghai Institute of Optics and Fine Mechanics (China)
Jianqiang Zhu, Shanghai Institute of Optics and Fine Mechanics (China)
Ping Zhu, Shanghai Institute of Optics and Fine Mechanics (China)
Meizhi Sun, Shanghai Institute of Optics and Fine Mechanics (China)
Qingwei Yang, Shanghai Institute of Optics and Fine Mechanics (China)
Haidong Zhu, Shanghai Institute of Optics and Fine Mechanics (China)
Ailin Guo, Shanghai Institute of Optics and Fine Mechanics (China)
Jun Kang, Shanghai Institute of Optics and Fine Mechanics (China)
Qi Gao, Shanghai Institute of Optics and Fine Mechanics (China)


Published in SPIE Proceedings Vol. 11034:
Short-pulse High-energy Lasers and Ultrafast Optical Technologies
Pavel Bakule; Constantin L. Haefner, Editor(s)

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