Fiber Fabry-Perot interferometer with mode-converting Bragg gratings

Bragg gratings are genuine narrow band reflectors. However, for several app lications narrow band transmission filters are of interest. It is demonstra ted that a pair of mode-converting Bragg gratings in a Fabry-Perot interfer ometer configuration yields a nonreflecting, narrow-band transmission filte r. A more detailed investigation shows further a different mode of operatio n where narrow band reflection occurs in resonance, It is shown experimenta lly how both modes of operation are attained by UV trimming of the Fabry-Pe rot interferometer, A mathematical model for the mode-converting Fabry-Pero t interferometer is given.