Study On Pumps' Scheme Of Broadband Fiber Raman Amplifiers

DWDM (Dense Wavelength Division Multiplexing) is the most efficient technology which can improves the capacity of optical fiber communication system remarkably, and EDFA can not meet the needs of DWDM for its limited gain bandwidth. Meanwhile, another amplifier named FRA (Fiber Raman Amplifier) gradually moves into people's view. FRA is an amplifier based on transmission fiber, and it belongs to the hot area of current research because of its excellent features: an ultra-broad -band amplifier, can amplify any wave band with suitable pumps, distributed amplification, good noise feature etc.The gain spectra of FRA with single pump are unevenness. In order to get the broader and more flat gain spectra, multiwave-pumping and optimizing the pumped lasers' wavelength and power are necessary. This paper studies pumps' scheme of broadband FRA.Firstly, solve the propagation equation of FRA by using the classic Runge-Kutta arithmetic iteratively, and the analysis includes all the interactions of pumps, signals, noise without any approximation. Compared with other arithmetic, this method has better precision and convergence.Secondly, use the PSO(Particle Swarm Optimization) optimizing the 6 pump lasers' wavelengths and power and make betterment, then a FRA with the gain ripple less than 0.6dB in100nm gain spectra is obtained. The FRA's gain bandwidth and gain flatness are better than other domestic results.Finally, the study's emphasis is laid on the ultra-broadband FRA. At first, three important parameters are investigated, and the results show that FRA's gain bandwidth, gain magnitude and gain flatness restrict each other and equilibrium is necessary for them. Then give a study of FRA's noise property and restraint methods. Finally, by optimizing 12 pumps' wavelengths and power, a FRA with flatness gain spectra of 135 nm which comprise the most part of S-band and nearly all of the C-band and L-band. The results show that FRA can be used as an ultra-broadband amplifier independently, with the unique feature of gain spectra bandwidth, FRA becomes one of the most promising ultra-broadband amplifiers in future.