Abstract: A method of writing a Bragg grating in a photosensitive optical waveguide (40) is disclosed comprising utilizing a single coherent beam of light (31) and a diffraction grating (32) to create two coherent working beams (33, 38) of light; positioning a plurality of reflective elements (35, 37) on each side of said waveguide; propagating the two working beams around said plurality of reflective elements, each of the beams being reflected by each of the reflective elements, so that the beams interfere at an initial predetermined position (45); and rotating at least one of the reflective elements on each side of the waveguide to simultaneously independently control the period of the interference pattern and position of the interference pattern in accordance with predetermined requirements so as to produce the grating structure in the photosensitive waveguide.