Optical glasses for high-peak-power laser applications

Only a limited number of optical glasses are commercially available that can be used in high-fluence laser applications between 0.35 and 1.05 micrometers . These include, primarily, certain phosphate glasses and fused silica. Phosphate glasses can now be made free of Pt-inclusions; the technology leading to this improvement is briefly discussed. In addition, inclusion-free fused silica can be made by a high temperature, chemical-vapor-deposition (CVD) process. Measured damage thresholds over a range of wavelengths and pulse lengths are reported for these materials. In addition, the use of doped layers of plasma CVD fused silica as a means of making high-damage-threshold rugate filters is presented. The impact of a high nonlinear refractive index (n2) on the spatial profile of the laser beam is discussed. Dramatic improvements in laser performance are possible if an inclusion-free, low-n2 glass (such as fluorophosphate) could be made. Multiphoton absorption and solarization of fused silica at 351 nm are also reviewed; fused silica continues to be the preferred material for high fluence applications at this wavelength.