تجزیه و تحلیل شبیه سازی تداخل بین کانال ها با تقویت کننده های رامان فیبر در 10 گیگا بایت / ثانیه

We have investigated the effects of crosstalk in fiber Raman amplifiers (FRAs) by propagating signals through the Raman fiber. We have observed that quality factor reduces for lesser channel spacing. We have able to propagate the signals in two channels with spacing of 20 GHz and quality factor above 25 dB was obtained. The effect of signal input power and injected pump power on crosstalk and signal interference ratio (SIR) has analyzed. It is observed that the signal gain and the injected pump power should be limited to the value well below the threshold of Raman amplification to ensure small crosstalk and high SIR. The effect of Raman fiber length on crosstalk is also studied and it is observed that for high values of Raman fiber length, SIR reduces considerably.

Wavelength division multiplexing (WDM) has enabled an explosive increase in the capacity of optical transmission systems with announced commercial systems reaching capacities beyond 1 Tb/s. The amplifiers based on Raman scattering enable the capacity of WDM systems to be increased [1]. The WDM is a technique in which number of optical signals from many different light sources having properly spaced peak emission wavelength are transmitted simultaneously over the same fiber. Thus, the use of multiple channels over the same fiber provides unprecedented transmission capacity. One of the main advantages of this technology is that a huge increase in available bandwidth can be obtained without deploying additional optical fiber [2]. Because of their broad band, Raman amplifiers are used to amplify several channels simultaneously in a WDM light wave system. The Raman amplifier offers much wider essential gain bandwidth [3]. The performance of a WDM system is strongly affected by an important parameter, called as crosstalk occurring between different channels. Crosstalk is defined as the interference in a communication channel caused by activity in other communications channels. The cause of crosstalk is some form of coupling mechanism between the disturbed channel and the disturbing channel. Coupling between channels is caused by the physical proximity and relative orientation of the transmission media. In this paper, we have investigated the crosstalk between two channels with Raman amplification by calculating quality factor and Signal interference ratio (SIR) for different values of signal input power and injected pump power. The impact of Raman fiber length on SIR has also been demonstrated.

It has been concluded that for multichannel transmission of signals through the Raman fiber, the optimum spacing between channels should be such that, there should be good quality factor (>25 dB) obtained. We are able to optimize this spacing to a value of 20 GHz for propagating two channels through the silica Raman fiber and obtained a quality factor of 27.5 dB. Further, at high values of signal input power and pump powers, SIR becomes poor. To ensure high SIR, the signal gain and the injected pump power must be restricted below the threshold value. Also, there is a net limitation on the choice of Raman fiber length. The SIR reduces for high values of this length. So, for getting high SIR, the Raman fiber length should be properly selected.