Mitigation of laser damage growth in fused silica by using a non-evaporative technique

• Published in: Chinese physics B Vol. 21; no. 5; pp. 316 - 322
• Main Author: 蒋勇 刘春明 罗成思 袁晓东 向霞 王海军 贺少勃 吕海兵 任玮 郑万国 祖小涛
• Format: Journal Article
• Language: English
• Published: 01.05.2012
• Subjects: Carbon dioxide lasers; Damage; Distortion; Energy density; Laser beams; Laser damage; Lasers; Plugs; Spots; 横向尺寸; 激光损伤阈值; 激光束; 石英; 缓解作用; 能量密度; 脉冲频率; 蒸发技术
• ISSN: 1674-1056; 2058-3834; 1741-4199
• DOI: 10.1088/1674-1056/21/5/054216

A non-evaporative technique is used to mitigate damage sites with lateral sizes in a range from 50 μm to 400 μm and depths smaller than 100 μm.The influence of the pulse frequency of a CO 2 laser on the mitigation effect is studied.It is found that a more symmetrical and smooth mitigation crater can be obtained by increasing the laser pulse frequency form 0.1 to 20 kHz.Furthermore,the sizes of laser-affected and distorted zones decrease with the increase of the laser pulse frequency,leading to less degradation of the wave-front quality of the conditioned sample.The energy density of the CO 2 laser beam is introduced for selecting the mitigation parameters.The damage sites can be successfully mitigated by increasing the energy density in a ramped way.Finally,the laser-induced damage threshold（LIDT） of the mitigated site is tested using 355 nm laser beam with a small spot（0.23 mm 2） and a large spot（3.14 mm 2）,separately.It is shown that the non-evaporative mitigation technique is a successful method to stop damage re-initiation since the average LIDTs of mitigated sites tested with small or large laser spots are higher than that of pristine material.