METHOD FOR FABRICATION OF IN-LINE OPTICAL WAVEGUIDE REFRACTIVE INDEX GRATINGS OF ANY LENGTH

摘要

A method and an apparatus for writing apodized Bragg gratings into an optical fiber. The method includes the steps of providing a photosensitive optical fiber and a writing beam. A periodic intensity distribution of period LAMBDA is created from the writing beam and the optical fiber is translated relative to the intensity distribution at a velocity v(t). The intensity of the writing beam is modulated as a function of time at a frequency f(t), where .v(t)/f(t) APPROX LAMBDA . The intensity of the writing beam is varied further to control the envelope of the refractive index profile to write apodized gratings.