The Electric Field Modulation by Hemisphere Damage Sites in Fused Silica Subsurface

Shaobo He,Xiao-Tao Zu,Li Li,Liang Yang

doi:10.1155/2014/843261

Abstract

The effect of defect density on the electric field modulation to incident laser is investigated in this work. Based on the actual defect distribution in fused silica subsurface, the three-dimension grid model of defect sites is constructed firstly. Then, the three-dimension finite-difference time-domain method is developed to solve the Maxwell equations. The electric field intensity in the vicinity of the defect sites located in front subsurface of fused silica is numerically calculated. The relationships between the maximal electric field intensity in fused silica and the geometry of the defect sites are given. The simulated results reveal that the modulation becomes more remarkable with the increase of defects density firstly and then decrease. Besides, the effect of the distribution mode of defects on modulation is discussed. Meanwhile, the possible physical mechanism is analyzed in detail.

Highlights

Laser damage of optics could be seen as occurring in two distinct steps
As laser damage cannot be inhibited totally, any laser damage on an optic may increase in severity by beam obscuration, intensity modulation, and light scatter
Some methods have been proposed to inhibit the growth of that laser damage, such as exposure of the SiO2 surface damage site to pulses from a CO2 laser, operating at 10.6 nm wavelength and sputtering the SiO2 surface damage site by some ion beam [4,5,6]

Summary

Introduction

Laser damage of optics could be seen as occurring in two distinct steps. The first one concerns the damage occurrence due to the first optic irradiation: the initiation step. The diagnosis of site and the nature of the precursors to the formation of the site are discussed mainly Such information is useful but must be taken in context when considering the design, construction, and operation of a major laser facility. Some methods have been proposed to inhibit the growth of that laser damage, such as exposure of the SiO2 surface damage site to pulses from a CO2 laser, operating at 10.6 nm wavelength and sputtering the SiO2 surface damage site by some ion beam [4,5,6]. The efficacy of the methods is inconclusive Both treatment of CO2 laser and sputtering of ion beam can smooth the damage site surface but can seldom fill any larger site.

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Conclusion