Effect of UV Laser Conditioning on the Structure of KDP Crystal

Decheng Guo,Xiaodong Jiang,Hongjie Liu,Xiaotao Zu,Fengrui Wang,Jing Huang

doi:10.1155/2014/451048

Abstract

Multiparametric raster scanning experiments for KDP crystals are carried out to study the laser conditioning efficiency as a function of laser fluence, fluence step, and pulse sequence by using ultraviolet (UV) laser irradiation with pulse duration of approximately 7 ns. It indicates that damage resistance of KDP can be enhanced after conditioning process. And laser conditioning efficiency depends on the maximal fluence which is below the damage threshold. Raman spectra and photothermal absorption have also been studied on KDP crystals before and after multiparametric laser conditioning. Photothermal absorption data reveal that absorbance of conditioned KDP crystal decreases with the increase of laser fluence and the damage threshold of low absorption area is higher. Raman analysis reveals that the effectiveness of laser conditioning relies mainly on the individual mode of PO4molecule.

Highlights

Potassium dihydrogen phosphate (KDP), with good physical properties including large nonlinear optical coefficient, good structural quality, and mechanical properties, is used in many large-aperture laser systems as frequency conversion crystal and electrooptic switching
Laser conditioning efficiency is largely determined by the preexposure laser parameters, such as laser fluence, wavelength, pulse number, and length [8, 9]
Negres et al reported the effectiveness of laser conditioning with 355 nm, 2.5 ns laser pulses with increasing fluence in deuterated potassium dihydrogen phosphate (DKDP) crystals as a function of fluence step and number of pulses per step

Summary

Introduction

Potassium dihydrogen phosphate (KDP), with good physical properties including large nonlinear optical coefficient, good structural quality, and mechanical properties, is used in many large-aperture laser systems as frequency conversion crystal and electrooptic switching. Negres et al reported the effectiveness of laser conditioning with 355 nm, 2.5 ns laser pulses with increasing fluence in deuterated potassium dihydrogen phosphate (DKDP) crystals as a function of fluence step and number of pulses per step. Their results demonstrate that a key laser parameter in achieving the best damage performance at 355 nm is the maximal fluence and that this parameter is material dependent [4].

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