Bragg gratings have been written in germanium-doped optical fibers that have been treated to remove the UV absorption bands associated with oxygen-deficient defects. When one is using high-intensity 193-nm light from an ArF excimer laser to fabricate the gratings, the refractive index increases and the grating transmission spectra are similar to those obtained in standard (untreated) fiber.
Optics Letters
Department of Electronics

Albert, J, Hill, K.O., Johnson, D.C., Bilodeau, F., Mihailov, S. J., Borrelli, N.F., & Amin, F. (1999). Bragg gratings in defect-free germanium-doped optical fibers. Optics Letters. doi:10.1364/OL.24.001266