The Study On The Compression Of Optical Pulse And Merging And Splitting Of Pulses In Optical Fibers

our research include two parts: one part, we study the compression of optical pulses in single-mode optical fibers. The other part, it is discussed the problem of transmission of optical pulse pair in nonlinear single-mode optical fibers.The technology of communication and information processing will be widely applied in prospect. In the technology, ultra-short pulse laser is important measure in not only fast transmission and acquirement of information but also capacity increasing of it. So, the generation of ultra-short pulse is the basic and key technology. Results of previous research indicate that it is an easy and feasible method to get ultra-short pulses by making use of effects of dispersion and nonlinearity of fibers to compress optical pulses. On the base of forenamed research, it is proposed to realize the compression of optical pulses by using effects of higher-order dispersion and higher-order nonlinearity in optical fibers. We discussed systemically the rule of compression of pulses in conventional fibers, dispersion-managed fibers, and dispersion-shifted fibers. The conclusion as follows:1. In conventional fibers, when the initial chirp of optical pulse is zero, higher-order solitons follow a periodic evolution patter of compression and broadening; with the increase of the peak power of incident soliton pulses, the compression ratio of output pulses increase and the optimum fiber length decrease, the quality of output pulses decrease. Considering the influence of positive third-order dispersion and Ramman-self-frequecy(RSS), the compression ratio of the output pulse decreases; For the influence of negative TOD and RSS, the compression ratio of the output pulse increase. For the influence of negative TOD and RSS, there is an optimum parameter of TOD that can make the compression ratio biggest. When the initial chirp of optical pulse is nonzero, the initial negative chirped pulse is compressed in positive dispersion fibers, the compression ratio decreases with the increase of the peak power of the input pulse; the initialpositive chirped pulse are compressed in negative dispersion fibers, the compression ratio increase with the increase of peak power of input pulses.2. The fundamental soliton can be compressed in dispersion-managed fibers. The compression ratio of output pulse decreases when considering the influence of higher-order effects. The compression ratio of output pulse decreases under the influents of positive TOD and RSS or negative TOD and RSS, the compression ratio of former is smaller than that of the latter and The optimum fiber length of former is smaller.3. In the dispersion-shifted fibers, it consists of copropagating a signal pulse with an intense pumping pulse in optical fibers whose minimum-dispersion wavelength is chosen such that it falls between the pump and the signal wavelength. When the width of the signal pulse is same to that of the pumping pulse, the signal pulse is compressed because of the influence of cross-phase modulation. With increase of the intensity of pumping pulse, the compression ratio of signal pulse increases, the peak power of output pulse increases, the optimum fiber length decreases and the quality of compression decreases, keeping the value!of N of the pumping pulse and the width of pumping pulse being smaller than that of the signal pulse, the compression ratio increases and the optimum fiber length decreases. On the contrary, keeping the value of N of the pumping pulse and the width of pumping pulse being bigger than that of the signal pulse, the compression ratio decreases and the optimum fiber length increases.In this paper, the other question is the merging and splitting of optical pulses by solving nonlinear Schr dinger equation numerically for the problem of transmission in nonlinear single-mode optical fibers. We study the trait and the physical principle of the merging and splitting of the pulses under the different intensities and analyze the pulse spectrum when pulses merging. There is a spectral band with the same cente...