Demonstration of negative refractive index photosensitivity mechanism in a phosphate glass optical fibre using 248nm, 500fs laser radiation

Several studies have been presented on the photosensitivity and index engineering of phosphate glasses using high intensity ultraviolet lasers. These studies are of particular interest due to the increased number of applications of rare-earth codoped phosphate glasses in the development of high efficiency planar and fibre active components. The authors present results on the Bragg grating recording behavior and photosensitivity of an all phosphate glass rare earth doped optical fibre, utilizing 248nm, 500fs laser radiation. In the grating inscription results presented, non-monotonic refractive index changes with respect to accumulated energy density are observed.