High-intensity UV laser inscription of fibre Bragg gratings and comparison with other fabrication techniques

摘要

Using high-intensity (around 200 GW/cm~2) femtosecond 264 nm laser light and phase mask technique, Bragg grating inscription in a range of different photosensitive and standard telecom fibres (both H_2-free and H_2-loaded) was studied. The dependencies of the induced refractive index modulation versus the incident fluence were compared with similar dependencies for gratings fabricated by other existing methods. It was shown that at high-intensity UV laser irradiation, two-quantum photoreactions occur in the irradiated fibre core, which results in a significant photosensitivity enhancement of the investigated fibres in comparison with conventional low-intensity 248 nm exposure (by 6-128 times, depending on fibre type and irradiation intensity).