In 1978. K. O. Hill and colleagues1 reported the formation of refractive index gratings in germanosilicate core, silica clad fibers by injection of 488 and 514.5 nm argon-ion laser radiation into one end of the core. A few years later, Lam and Garside2 showed the grating strength increased as the square of the power flux, suggesting a two-photon process as responsible for the photo-induced changes. Quite apart from these experiments, other researchers3–4 observed in fused germania and germania-doped silicate glasses the presence of an intense UV absorption band at 244.5 nm thought to be due to oxygen vacancy defects. Our experiments show that Bragg gratings can be created in photo-refractive germanosilicate fiber5 and in specially prepared germania wafers by lateral exposure of the core to an ultraviolet two-beam interference pattern at a wavelength which lies in the 244.5 nm band. It is believed that the index changes are due to the bleaching of this band. This paper describes these experiments and presents measurements of the in-fiber filter characteristics obtained by the two-beam holographic exposure method. We discuss and illustrate how the gratings can be used to form wavelength-selective, tandem temperature and strain sensing regions in a single fiber.