Assessment of waveguide thermal response by interrogation of UV written planar gratings

The technique of direct grating writing, based on direct ultraviolet writing, is demonstrated as a tool for highly accurate measurement of waveguide and material properties. Silica-on-silicon planar samples are processed using hydrogen loading and thermal locking before Bragg channel waveguides are defined in the photosensitive core layer. The refractive index is accurately probed to compare different thermal locking procedures and characterize waveguide thermal stability.