To inspect the treatment effect of high power plasma on fused silica, inductively coupled plasma with power of 36kW at atmospheric pressure , CF4 as working gas, was applied to carry out the etching experiments of fused silica, in which the effect of CF4 flow rate on material remove rate, surface roughness and surface profile were investigated. The experimental results showed that the material remove mechanism of fused silica treated by high power inductively coupled plasma was a result of the comprehensive effect of melting and evaporation at high temperature, chemical etching and bombardment of high energy ions. The fused silica remove rate reached 0.208g/min with the CF4 flow rate of 2.8L/min. The surfaces of fused silica samples became rougher with the increased CF4 flow rate, as the subsurface micro-cracks were opened and formed etching pits by the plasma etching. The surface global profile was affected seriously by the distance between outer plasma flame and samples while the local profile was dominated by etching pits.
Fused silica is used as windows or lens in high power laser system. Slight laser absorption in it may results in huge damage caused by thermal effects. In order to reduce the bulk optical absorption in fused silica, mechanism of laser absorption in fused silica was studied from the perspective of structural defects. Ultra-purity fused silica was synthesized by high frequency plasma chemical vapor deposition (PCVD) process. Characteristics of structural defects includes hydroxyl, metal impurities, oxygen vacancy, bubbles and invisible stripe were studied by transmission spectrum, infrared reflection spectrum, stress birefringence, confocal microscope and impurity analyses. Formation mechanism of structural defects in fused silica was analyzed according to deposition process and vitrifying mechanism of silica. And influence of structural defects on bulk optical absorption was analyzed. By controlling structural defects, ultra-low laser absorption fused silica was synthesized by PCVD process.
The fused silica glass is widely used in the photoelectricity and semiconductor industry, and needed to be cut or made small holes and micro grooves on it. Recent reports indicate that laser processing is one of important means for fused silica glass. First of all, the laser processing characteristics of fused silica glass was discussed in this paper. Besides, 532nm wavelength and CO2 laser were used to process or cut fused silica glass, and different results were found. 532nm laser is more suitable for processing holes and micro grooves on thin fused silica glass. Then CO2 laser can be used to cut thick fused silica plate or marked on the glass surface. In addition, the two laser machined surface was observed with 3D microscope, and it displays huge surface differences. The first one is rough, and another is smooth.