Multiwavelength irradiation effect in fused quartz ablation using vacuum-ultraviolet Raman laser

Simultaneous multiwavelength irradiation of a vacuum-ultraviolet (VUV) Raman laser presents high-quality microfabrication of fused quartz by ablation. In order to make the mechanism of high-quality ablation clear, both of stationary and transitional absorption changes of a fundamental beam (266 nm) in fused quartz induced by short wavelength components were examined. The stationary change is caused by photodissociation of Si-O bonds and formation of metastable absorption sites, while the transitional change is attributed to excited-state absorption (ESA) due to coupling of the VUV components and the fundamental beams. Comparison of magnitude of the absorption changes between both effects indicates that the transitional effect is dominant in the process.