Strong (>20 dB) long-period fibre gratings were fabricated by combining F-2-laser photosensitivity-locking of hydrogen-soaked telecommunication fibre and KrF-laser grating formation, The 157 run pretreatment permanently enhances the fibre photosensitivity response to the low-energy 248 rum photons. Thermal annealing at 120degreesC for 24 h improves the grating stability without diminishing the enhancement.