The Study Of Gain Properties Of Distributed Fiber Raman Amplifier

With the fast development of Internet and other data communication, the capabilitydemand of long-haul fiber communication system is increasing dramatically. Fiber RamanAmplifier has the character of wind-band and on-line amplification; therefore it gets moreand more attention. In this thesis, the theory of distributed fiber Raman amplifier is given,then simulation analysis and experiments are operated on the gain properties of fiber Ramanamplifier. The results of the experiments and the simulation agree well. The main researchcontents and results are given as follows: (1) The characters of several kinds of optical amplifiers are compared. And theproperties, applications and developments of fiber Raman amplifier are recounted. (2) The basic theory of Raman scattering and the characteristics of stimulated Ramanscattering in fiber are detailed. The properties of fiber Raman amplifier are discussed,including gain property, noise property, polarization correlation and temperature stability. (3) The numerical model of fiber Raman amplifier is given first. Simulation analysis isactualized using simulation software based on the model. The backward- pump model iscompared with the forward-pump model, and the conclusion that the backward-pumpamplifier operates better is gotten. The calculation and optimization of fiber length is done.High saturation power property of fiber Raman amplifier is approved from the simulationthat the gain changes with signal power. The linear amplification property of fiber Ramanamplifier is verified from the simulation that the gain changes with pump power. (4) The experiment scheme on the gain of fiber Raman amplifier is introduced and aseries of experiments are conducted. The relationship of gain coefficient and frequency shiftis calculated from the result of experiment. The research on the relationship of small signalgain and signal power is conducted through experiments, and so does the research on therelationship of gain and pump power. (5) Much simulation analysis on gain flattening is given, followed by manyexperiments. About C-band amplification, the pump module has two wavelengths. Theresult of simulation and experiment agrees well when the power of one pump increases or IIdecreases. A gain variation of 1.5dB is realized at present. About C+L band amplification,the pump module has four wavelengths. The contribution of each pump to the gain spectrumis simulated and it is verified that gain flattening can be realized by changing some pumppower. A gain variation of 1dB is realized at present.