Correlation of defect centers with a wavelength-dependent photosensitive response in germania-doped silica optical...

We demonstrate a similar wavelength-dependent response for both the generation of Ge E' centers and the formation of photosensitive gratings in germania-doped silica fibers. This supports a model for the grating formation whereby two-photon absorption of laser radiation into the UV bleachable absorption band of an oxygendeficient germania site creates hole traps, modeled as Ge E' centers, which are detectable with electron spin reasonance spectroscopy.