Fiber Raman Amplifier Gain Flattening Research And Application

With optical fiber communication and multi-media technology quickly developing, IPTV, video phone, long-distance learning, long-distance medication, e-library, e-office etc. gradually come into the people抯life. During this process, fiber Raman amplifier (FRA) will play a very important role, especially in the future backbone and metropolitan area network, due to its lots of advantages known to us. But the real use of FRA will strongly depends on two important factors, namely high power pump laser and gain flattening spectrum. With high power pump laser technology becoming more and more mature, the gain flattening design becomes the most important factor we should consider. This thesis will focus on gain flattening problem research of RFA as well as its relative experiments. Besides, this thesis will also do some application research of FRA in the real optical communication system.As beginning of this thesis, it will briefly introduce the development of optical fiber communication and FRA as well as the significance of gain flattening research of RFA. And then we will emphasize the theory, stimulation and relative experiments of gain flattening of FRA as follows:Firstly, this paper will use single-step and multi-step average power algorithm to solve the transferring function of multi-pump and multi-signal FRA. This work will point to the three-wavelength fiber Raman laser we have as amplifier pump power (its wavelengths are 1428 nm, 1445nm, 1466 nm respectively). It will optimize this laser input pump power for obtaining wide-band gain flattening spectrum of FRA using previous algorithm and will also use experiment to testify it.Secondly, for single-pump gain flattening solution, we use 1427nm and 1455nm fiber Raman laser as pump source for S-band and C-band FRA respectively. Because the gain flattening characteristic of single pump solution, this thesis will design appropriate gain flattening filter for them according its benchmark gain and designated wideband of FRA. The types of filter we choose and design theoretically are long period fiber grating (LPFG) filter and chirped fiber Bragg grating (CFBG) gain flattening filter. In relative experiment, the final gain flattening filter we use is CFBG. Thirdly, this paper will discuss the nonlinearity phenomenon of stimulated Brillouin scattering (SBS) in FRA, its effect to design of RFA and its corresponding solution for gain flattening filter.Finally, for proving the performance and features of our designed FRA, we did some FRA application experiments in the real fiber communication system (namely in campus network and radio over fiber (RoF) communication system respectively).