Method of forming a dispersing grating in an optical fiber

摘要

A laser source supplies a primary laser beam. A phase grating generates two secondary beams from the primary beam so as to form interference fringes that are inscribed in an optical fiber by photo-refraction. An optical system of variable focal length varies the gap between the interference fringes so as to vary the pitch of the Bragg grating discretely for successive segments of the optical fiber. Means displace the primary laser beam and the optical fiber relative to each other by successive segments of said fiber. These means are synchronized with the variation of the focal length of the optical system. Application to telecommunications.