Abstract

In high-energy laser systems, the energy absorption coefficient of silicon optical elements is one of the most critical performance indicators. The absorption coefficient of substrate limits the absorption of the overall elements. Since mono-crystalline silicon is transparent in working wavelength range, the subsurface absorption precursors also influence the entire absorption dramatically. In this paper, the subsurface of a super-polished silicon substrate is exposed by ion beam etching (IBE) as deep as 4.6 μm. In different depth layers, morphology and energy absorption are measured with an atom force microscope and photothermal instrument, respectively. In the 100 nm layer, microstructures are found, and their heights decrease while widths increase with IBE. Finally, structures are diminished below the 1.12 μm layer. Absorption increases with the structures’ appearance. When the structures are fully exposed, absorption reaches the peak value, 327.5% of the unremoved surface. Once structures are removed, the absorption value falls down to the lowest point, 67.5%, which verifies that structures influence the absorption significantly. According to the structure depth and energy dispersive spectrometer results, the structures are most likely the densificated micro zones, generated by fabrication processes. In practical fabrication, a subsurface layer of 1.12 μm thick needs to be removed by stress-less processes, to obtain a low-absorption element.

© 2017 Optical Society of America

Investigation of surface damage precursor evolutions and laser-induced damage threshold improvement mechanism during Ion beam etching of fused silica

Feng Shi, Yaoyu Zhong, Yifan Dai, Xiaoqiang Peng, Mingjin Xu, and Tingting Sui
Opt. Express 24(18) 20842-20854 (2016)

Investigation of laser-induced damage threshold improvement mechanism during ion beam sputtering of fused silica

Mingjin Xu, Feng Shi, Lin Zhou, Yifan Dai, Xiaoqiang Peng, and Wenlin Liao
Opt. Express 25(23) 29260-29271 (2017)

Detailed near-surface nanoscale damage precursor measurement and characterization of fused silica optics assisted by ion beam etching

Yaoyu Zhong, Feng Shi, Ye Tian, Yifan Dai, Ci Song, Wanli Zhang, and Zhifan Lin
Opt. Express 27(8) 10826-10838 (2019)

Argon plasma etching of fused silica substrates for manufacturing high laser damage resistance optical interference coatings

Kęstutis Juškevičius, Rytis Buzelis, Giedrius Abromavičius, Romanas Samuilovas, Saulė Abbas, Alexandr Belosludtsev, Ramutis Drazdys, and Simonas Kičas
Opt. Mater. Express 7(10) 3598-3607 (2017)

Detailed subsurface damage measurement and efficient damage-free fabrication of fused silica optics assisted by ion beam sputtering

Wenlin Liao, Yifan Dai, Zongzheng Liu, Xuhui Xie, Xuqing Nie, and Mingjin Xu
Opt. Express 24(4) 4247-4257 (2016)