Improvement of deep-ultraviolet transparency of silica glass by control of point defects

Silica glass (amophous SiO2) is a simple oxide glass and the constituents (Si and O) are both ubiquitous elements. Furthermore, silica glass has various distinct properties, including an excellent transparency from infrared to vacuum-ultraviolet (VUV, <200nm) spectral region, good chemical stability and radiation hardness, and high mechanical strength. However, optical properties of silica glasses are often influenced by the presence of point defects, whose typical concentrations are as small as ppm level. We are studying defect processes in silica glasses and ways to develop silica glasses used with intense VUV and deep-ultraviolet (DUV, <300nm) lasers by controlling the defect processes.