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 CO<sub>2</sub> 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 CO<sub>2</sub> 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.
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.