Absence of UV-Induced Stress in Bragg Gratings Recorded by high-intensity 264 nm Laser Pulses in a Hydrogenated SMF-28

We report on photochemical two-photon Bragg grating preparation in hydrogenated fiber without any UV-induced stress in the core or cladding, leaving only the color-center model responsible for refractive index changes for UV femtosecond irradiation.