• High Power Laser Science and Engineering
  • Vol. 4, Issue 1, 010000e9 (2016)
Bingyan Wang1、2, Junyong Zhang1, Shuang Shi1、2, Kewei You1、2, and Jianqiang Zhu1
Author Affiliations
  • 1Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
  • 2University of Chinese Academy of Sciences, Beijing 100049, China
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    Abstract

    The processing method applied to the side surface is different from the method applied to the light pass surface in neodymium phosphate glass (Nd:glass), and thus subsurface defects remain after processing. The subsurface defects in the side surface influence the gain uniformity of Nd:glass, which is a key factor to evaluate the performance of amplifiers. The scattering characteristics of side subsurface defects were simulated by finite difference time domain (FDTD) Solutions software. The scattering powers of the glass fabricated by a computer numerical control (CNC) machine without cladding were tested at different incident angles. The trend of the curve was similar to the simulated result, while the smallest point was different with the complex true morphology. The simulation showed that the equivalent residual reflectivity of the cladding glass can be more than 0.1% when the number of defects in a single gridding is greater than 50.

    1 Introduction

    A disk amplifier pumped by flash lamps is the primary main amplifier in lasers at the mega joule (MJ) level. Beamlet[1], the National Ignition Facility (NIF)[2] developed by Livermore in America, the LMJ[3] building at French Atomic Energy Commission, SG II[4] and SG III[5] in China are the typical MJ lasers, in which disk amplifiers are employed to magnify energy. The main gain medium in disk amplifiers is neodymium phosphate glass (Nd:glass)[6], whose energy conversion efficiency determines the gain of the amplifier directly. When clear aperture is increased, the amplified spontaneous emission (ASE) and parasitic oscillation (PO) decrease the gain uniformity of Nd:glass intensely[7]. In order to suppress the ASE and PO, cladding is used on the side of the glass[8, 9]. There are many ways to realize cladding, for example, sealing cladding[10], liquid cladding[11], polymer edge cladding[12], thin film coatings[13], and so on. The research on cladding has focused on the structures of cladding, while the influences of the defects induced by the process of glass on the properties of cladding have been less well studied.

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    Bingyan Wang, Junyong Zhang, Shuang Shi, Kewei You, Jianqiang Zhu. Effects of side subsurface defects induced by CNC machine on the gain spatial distribution in neodymium phosphate glass[J]. High Power Laser Science and Engineering, 2016, 4(1): 010000e9
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    Received: Jan. 4, 2016
    Accepted: Feb. 2, 2016
    Published Online: Oct. 25, 2016
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