Narrowband fiber-optic phase-shifted Fabry-Perot Bragg grating filters for atmospheric water vapor lidar measurements

A unique ultranarrowband fiber-optic phase-shifted Fabry-Perot Bragg grating filter for atmospheric water vapor lidar measurements was designed, fabricated, and successfully tested. Customized optical fiber Bragg gratings were fabricated so that two transmission filter peaks occurred: one (89% transmission, 8 pm FWHM) near the 946-nm water vapor absorption line and the other peak (80% transmission, 4 pm FWHM) at a region of no absorption. Both transmission peaks were within a 2.66-nm stop band. Demonstration of tension tuning to the 946.0003-nm water vapor line was achieved, and the performance characterization of custom-made optical fiber Bragg grating filters are presented. These measurements are successfully compared to theoretical calculations using a piecewise-matrix form of the coupled-mode equations.