Spatial characterization of strong fiber Bragg gratings using thermal chirp and optical-frequency-domain reflectometry

A method that can spatially characterize gratings with grating strength |/spl kappa/|L up to 10 is presented. The grating is thermally chirped, which increases the transmissivity through the grating. The complex reflectivity spectrum is measured using optical-frequency-domain reflectometry, and the spatial profile is reconstructed using the time-domain layer-peeling algorithm. The spatial profiles of a uniform grating with grating strength |/spl kappa/|L = 8.25 (-66-dB minimum transmissivity) and a distributed-feedback fiber laser grating with grating strength |/spl kappa/|L = 7.5 are accurately reconstructed from the measured complex reflection spectrum.