Effects of Ion Beam Etching on the Nanoscale Damage Precursor Evolution of Fused Silica

Abstract

Nanoscale laser damage precursors generated from fabrication have emerged as a new bottleneck that limits the laser damage resistance improvement of fused silica optics. In this paper, ion beam etching (IBE) technology is performed to investigate the evolutions of some nanoscale damage precursors (such as contamination and chemical structural defects) in different ion beam etched depths. Surface material structure analyses and laser damage resistance measurements are conducted. The results reveal that IBE has an evident cleaning effect on surfaces. Impurity contamination beneath the polishing redeposition layer can be mitigated through IBE. Chemical structural defects can be significantly reduced, and surface densification is weakened after IBE without damaging the precision of the fused silica surface. The photothermal absorption on the fused silica surface can be decreased by 41.2%, and the laser-induced damage threshold can be raised by 15.2% after IBE at 250 nm. This work serves as an important reference for characterizing nanoscale damage precursors and using IBE technology to increase the laser damage resistance of fused silica optics.

Исследование Поверхностного Слоя, Образующегося При Обработке Кварцевого Стекла С Помощью Механохимического И Ионного Полирования

“…Изучение ПС кварцевого стекла методом спектроскопии комбинационного рассеяния показывает, что в результате бомбардировки ионами Ar + в ПС возникают деформированные мостики Si−O−Si с напряженными связями. Эти связи образуют структурные кольцевые образования: пик D1 -490 сm −1 и пик D2 -605 сm −1 соответственно в 4-и 3-членных кольцевых структурах [59]. Относительные интенсивности пиков D1 и D2 первоначально увеличиваются, когда глубина травления ионным пучком составляет 50 nm, что свидетельствует об удалении грубых наноразмерных структурных дефектов в ПС и увеличении степени уплотнения по сравнению с исходной поверхностью.…”

Statistically Correlating Laser-Induced Damage Performance with Photothermal Absorption for Fused Silica Optics in a High-Power Laser System

“…For example, Ju et al demonstrated the laser damage degree on fused silica surface can be indicated through combining photothermal spectroscopy and optical microscope [24]. Zhong et al utilized photothermal spectroscopy to characterize nanoscale damage precursors on plasma-etched fused silica surfaces [25,26]. Despite these great efforts, the correlation between defects at various absorption levels and damage performance on fused silica surfaces is still not fully clarified due to the complexity of these absorbing defects.…”

Fused silica with sub‐angstrom roughness and minimal surface defects polished by ultrafine nano‐CeO2

“…Fused silica with high‐temperature resistance, chemical inertness, and outstanding transmittance from ultraviolet to infrared wavelength range is widely used in laser gyroscope, high‐power lasers, and ultraviolet lithography systems 1–4 . With the shortening of wavelength, the increase of power, and the improvement of system accuracy, it is urgent to achieve super smooth and defect‐free surface of fused silica to reduce optical scattering and loss as well as laser modulation, which are principally caused by surface defect and roughness 5–7 . It has been proved that the total integrated scatter of the optical component to be proportional to the square of the root‐mean‐square value of the surface roughness, 8–9 so the reduction of surface roughness is of great significance to improve the transmittance of optical components and the precision of optical imaging systems.…”

“…[1][2][3][4] With the shortening of wavelength, the increase of power, and the improvement of system accuracy, it is urgent to achieve super smooth and defect-free surface of fused silica to reduce optical scattering and loss as well as laser modulation, which are principally caused by surface defect and roughness. [5][6][7] It has been proved that the total integrated scatter of the optical component to be proportional to the square of the root-mean-square value of the surface roughness, [8][9] so the reduction of surface roughness is of great significance to improve the transmittance of optical components and the precision of optical imaging systems. Besides, surface defects can greatly reduce the laser-induced damage threshold of fused silica by weakening the mechanical properties, modulating the incident light field, and embedding absorptive impurities.…”