<title>Optical design based on genetic algorithm of distributed fiber Raman amplifier cascades</title>

Redistribution of pump power and impairments in gain-equalized distributed fiber Raman amplifiers due to four-wave mixing and parametric amplification

“…The mathematical model used here to describe the interaction of SRS and FWM processes in a co-propagating Raman pump configuration can be derived from the expressions given in [3][4][5][6][7][8]. It describes the propagation of a lightwave at frequency f F in direction +z, which interacts by SRS with other waves at different frequencies f j .…”

“…In order to analyze the effects produced by parametric gain and FWM on the propagation of co-propagating Raman pumps along a DFRA, three co-pumped WDM systems were designed with flat gain by using the optimization method described in [5]. The objective of this method is to find the wavelength and power of each Raman pump in a DFRA, aiming at compensating the fiber attenuation, and providing a flat output power spectrum for all WDM channels involved.…”

“…Nevertheless, the expected performance of a multi-pumped DFRA for broadband systems is mainly determined by the efficiency and rigorousness of the method used to design it [1,2]. Several techniques have been proposed to optimize the spectral gain profile of a DFRA in order to provide a flat gain for all the wavelength division multiplexed (WDM) channels in the system [2][3][4][5][6]. The objective of all these methods is to find both the optimum spectral position and the input power of every pump of the amplifier.…”

Pump-Pump Four-Wave Mixing in Distributed Fiber Raman Amplifiers

“…In this case, 20 depolarized WDM channels, with an input power of 0.5 mW/ch and placed in the range [1540-1560] nm, are amplified along 50 km of TWSMF. The amplifier is designed through an optimization method based on genetic algorithms, [2] and [3], to find the wavelength and power of each pump, with the purpose of obtaining the flattest net gain in the WDM bandwidth. As a result of the design, 3 laser pumps are obtained; they are placed at 1420.28 nm, 1438.14 nm and 1463.52 nm with 160.93 mW, 92.24 mW and 99.61 mW of input power, respectively.…”

“…The advantages of DFRAs compared to Erbium-Doped Fiber Amplifiers (EDFAs) are related to design flexibility, broad gain bandwidth, low noise and its capacity to reduce the effect of fiber nonlinearities [1]. However, the good performance of a DFRA is dramatically determined by the mathematical model and the method used to design it [2,3]. DFRAs working with low chromatic dispersion fibers or with pumping waves located near the zero dispersion wavelength ( ZD ) require the development of numerical models that include other nonlinearities such as four wave mixing (FWM) [4][5][6].…”