Abstract
Two kinds of special long period fiber gratings, phase shift and apodised long period gratings, were studied by many researchers, because of their special spectral charateristics. According to the thoery of long-period moir e gratings, with the methods of step-by-step ultraviolet (UV) writing and double exposure with different grating period, several kinds of long-period moir e gratings were fabricated in the hydrogened high germanium doped fiber by controlling the period, several kinds of long period moir egratings were fabricated in the hydrogened high germanium doped fiber by controlling the period and the first position of both exposure and the exposure time of each step, which realized the effects of phase shift and apodization.