Apparatus and process for making fiber optic bragg gratings

Apparatus for forming a Bragg grating in an optical fiber comprising:

• a mirror having a reflecting surface;
• means for generating a coherent beam of monochromatic light and directing the beam in a first direction so that at least part of the beam is an incident beam, incident, in said first direction, on the reflecting surface of the mirror;
• the reflecting surface of the mirror being oblique with respect to said first direction so that the incident beam is reflected to produce a reflected beam in a second direction different from the first direction and the reflected beam intersects the beam directed in the first direction, whereby an interference pattern is produced within a volume defined by the intersection of the beam directed in the first direction and the reflected beam;
• and
• means for supporting an optical fiber so that at least a part of the fiber is within said volume;
• whereby a grating is photo-induced in the optical fiber by the interference pattern.