Theoretical and experimental investigations on Sagnac interferometer basedon single optical fiber grating

A novel Sagnac interferometer employing an optical fiber grating in its loo p is presented. The transmission responses of the loops with uniform Bragg gratings and linearly chirped fiber gratings are calculated. The analytic e xpressions for the loop with a uniform Bragg grating are given. It is found that the loop of a uniform grating leads to equally spaced bandpasses,whil e that of a chirped fiber grating leads to unequally spaced band-passes. Su ch Sagnac loops may find applications in dense wavelength division multiple xing (DWDM) systems and optical fiber sensing. The multiple band-passes fil ters with 8 and 16 channels are demonstrated experimentally. The experiment s verify the results of our analysis.