Combined modulation of incident laser light by multiple surface scratches and their effects on the laser damage properties of KH2PO4 crystal.
Combined modulation of incident laser light by multiple surface scratches and their effects on the laser damage properties of KH2PO4 crystal.
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DOI：
10.1364/oe.388741
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发表时间：
2020-03
期刊：
影响因子：
3.8
通讯作者：
Jian Cheng;Jinghe Wang;E. Peng;Hao Yang;Hao Chen;Mingjun Chen;Jiubin Tan
中科院分区：
文献类型：
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作者：
Jian Cheng;Jinghe Wang;E. Peng;Hao Yang;Hao Chen;Mingjun Chen;Jiubin Tan
加工引起的表面缺陷被认为是一个潜在的来源，导致实际的KDP晶体光学器件的激光诱导损伤阈值（LIDT）远低于本征之一。然而，其内在机制尚未得到充分认识。通过对KDP光学器件的光强度建模和激光损伤实验，研究了多道划痕对入射激光的联合调制及其对KDP光学器件激光损伤性能的影响。在多个划痕的联合调制下，由于被相邻划痕包围的凸透镜轮廓的聚焦效应，产生增强的热点。组合调制作用比单个划痕强得多。多道划痕引起的相对光强度（IR）可达两倍，热点（IP）的数量是单道划痕的四倍。随着划痕密度的增加，IR表现出普遍的增加趋势。但对于后表面划痕的双全反射情况，全反射光通过相邻的划痕透射，导致IR下降的趋势。随着划痕密度的增加，测试的LIDT和多个划痕的光学透射率呈现逐渐减小的趋势，这与模拟结果一致。此外，模拟得到的光强度能够很好地解释激光损伤的位置，进一步验证了多道划痕在降低抗激光损伤能力中的作用。
Manufacturing-induced surface defects are deemed as a potential source, leading the laser-induced damage threshold (LIDT) of the actual KDP crystal optics to be much lower than the intrinsic one. However, the underlying mechanisms have not been fully recognized. We explore the combined modulation of incident laser light by multiple scratches and their effects on laser damage performance of KDP optics by modeling the light intensifications and performing a laser damage test. Under the combined modulation of multiple scratches, enhanced hot spots are generated due to the focusing effects of convex lens profiles surrounded by the neighboring scratches. The combined modulation actions are much stronger than that of a single scratch. The relative light intensities (IRs) caused by multiple scratches can reach up to two times, and the number of hot spots (IPs) are four times as large as those by a single scratch. The IRs exhibit a general, increasing tendency as the scratch density increases. But for the case of double total reflections of rear-surface scratches, the totally reflected lights are transmitted through neighboring scratches, resulting in decreasing tendency of IRs. The tested LIDTs and optical transmittances of multiple scratches present a gradual, decreasing tendency with the increase of scratch density, which agrees with the simulation results. Besides, the simulated light intensifications could well explain the locations of laser damage, which further verify the role of multiple scratches in lowering the laser damage resistance.