Light propagation and localization in randomly spaced gratings in a single mode fiber

Summary form only given. We present a study of light propagation in a randomly spaced fiber grating system, showing localization properties. The transmittance decay has an exponential dependence on the number of gratings, in accordance with the localization theory. The interesting feature is that the result contradicts the naive ray theory assumption that the random phases, associated with the randomly varying spacing between the gratings make the system incoherent. Then one would expect a T/sub N/ /spl prop/ T/N dependence for the N gratings intensity transmittance, where T is the single grating transmittance. The study here, along the known results of the localization theory, shows that the decay is exponential, T/sub N/ = exp[-Nlog(1/7)], and the multiple internal reflections between the different gratings tend to cancel in the transmittance due to destructive interference. The result can be of interest for uses of long random grating arrays, as well as for the study of localization in ideal 1-dimensional systems.