Fiber gratings irradiated by CW-laser show a breaking strength and a lifetime performance similar to that of pristine fiber, on pulsed KrF-laser irradiation. In this paper we report on the mechanical reliability of fibers irradiated by UV light using the side exposure technique. Homogeneous excimer laser irradiation reduces the mechanical resistance considerably depending on the fluence per pulse and the laser wavelength. With increasing pulse energy density the mechanical resistance is lowered. In contrary, homogeneous CW irradiated fibers show almost the same fiber strength as compared with pristine fiber