SPAR-K: Semiconductor Patterning for Anti-Reflection on KGW

Modern high energy laser systems require nonlinear laser crystals that can handle large optical intensities to drive efficient optical nonlinear processes. Anti-reflection treatments for the facets of these crystals are required for optimum performance. Unfortunately, traditional coatings based on dielectric stacks are prone to failure, often due to thermal shock. Surface texturing is a promising alternative technical pathway towards anti-reflection treatment of the facets of nonlinear crystals. However, standard surface texturing processes are strongly material dependent and therefore require a renewed research effort with every laser crystal type. In response, PSI has developed the semiconductor patterning for antireflection (SPA) treatment, which is highly substrate agnostic as patterning is performed using a pre-defined 3D semiconductor mask. Specifically, in this program PSI will target the antireflection surface treatment of tungstate materials. The proposed process is scalable to large substrate areas and unconventional substrate geometries. Moreover, the process is highly tunable and enables fine control of surface texture spacing, thickness, and nanostructure geometry allowing the surface coatings to be adapted for wavelength bands ranging from the visible to infrared.