Rayleigh longitudinal profiling of optical resonances within waveguide grating structures using sidescattered light

The resonant characteristics of Bragg gratings in fibers are characterized by measurement of the wavelength dependence of the Rayleigh scattering of light propagating in the core along the grating length. This technique is found to give information on the standing-wave intensity profile in the grating that cannot be deduced from the standard transmission or reflection spectra.