Investigation On Slow Light Of Uniform Fiber Bragg Gratings

As a new kind of passive photonic devices, the fiber Bragg gratings have several distinguished advantages, such as low insertion loss, small bulk, potentially low cost, insensitive to polarization, simply spliced into fiber systems, and the emergence of slow light can be used to solve the most important problems such as optical storage, buffer and sensor and so on, which has wide applications in optical fiber communications and optical fiber sensing fields, and became a hot spot in the field of optics during the last decade.In this paper, the influence of core diameter, core index, relative index difference,"dc"index change spatially averaged over a grating period, fringe visibility of the index change, grating length and grating period on group delay of uniform fiber Bragg gratings was investigated by numerical simulation method, the effect of different parameters on the maximum value of the group delay was discussed in detail, the maximum value of the group delay was achieved through changing the parameters and the slow light of this kind of gratings based on the group delay versus the slow light was presented emphatically.The result shows:(1) The group delay curves move to the right with core diameter, core index,"dc"index change spatially averaged over a grating period, fringe visibility of the index change, grating length and grating period, but it move to the left with relative index difference.(2) The group delay-wavelength curve of the deviation degrees with core index is longest and increases with"dc"index change spatially averaged over a grating period, fringe visibility of the index change and grating length increasing, but decreases with core diameter, core index, relative index difference and grating period increasing.(3) At same time, the maximum group delay increases with relative index difference,"dc"index change spatially averaged over a grating period, fringe visibility of the index change, grating length increasing, but the maximum group delay decreases with core diameter, core index and grating period increasing and the rules of impact vary with the parameters and can be reached to 17μs.(4) Especially the slow light decreases as a function of wavelength increasing, which rapidly reduced to 0ns from 17μs and shocks of the deviation is no more than wavelength of 0.01nm. It shows that the slow light delay conducted by this kind of gratings is rapidly decaying.