In-phase stitching of long fiber gratings

摘要

A method and apparatus for fabricating an optical waveguide grating by writing a succession of grating sections into a photosensitive waveguide. A first grating section is written by repeatedly exposing an inscription beam having a periodic intensity pattern onto the first length of the waveguide and moving the inscription beam relative to the waveguide between successive exposures. After writing the first grating section, the waveguide is moved on the translation device so that a second length of the waveguide is arranged for exposure, but with a portion of the first grating section remaining in range of the linear translation device. A probe beam having a periodic intensity pattern is used to illuminate the portion of the first grating section. The phase relation between the intensity pattern of the probe beam and the first grating section is then determined by translating the waveguide relative to the probe beam and measuring fluorescence emitted from the waveguide excited by the probe beam. Writing of the second grating section then proceeds.