UV written 1.5 mu m reflection filters in single mode planar silica guides

The authors report for the first time a grating in GeO 2 -SiO 2 planar waveguides formed by exposure to UV radiation. The grating gave a reflectivity or 44% with a bandwidth or 1.1 nm, which indicates an index modulation or at least 2.0×10 -4 . The waveguide material was made sensitive to the UV radiation by annealing in H 2 , which significantly enhanced the 240 nm absorption band