Engineering Flat Gain Tunable Raman-Parametric Hybrid L-Band Amplifier for Narrow Band Multi-Channel Terabits System

Abstract

We present a model of a Raman-parametric hybrid amplifier for flat gain amplification of narrowband Dense Wavelength Division Multiplexed (DWDM) terabits capacity system. In the proposed configuration Raman pump has been cascaded with one – pump parametric amplifier. While Raman amplifier typically uses a long length single mode fiber as a gain medium, the Fiber Optical Parametric Amplifiers (FOPA) uses a small length of Highly Non-Linear Fibers (HNLF). This allows for maximum optimization of the gain achieved using Raman as well as parametric processes. We focus on the signal degradation due to non-linear crosstalk arising because of multi-pump configuration, in particular, due to the generated idlers within the operational bandwidth. As the channel spacing is reduced, fiber non-linearities increase significantly. The dilemma to use the fewer number of high powered pumps Vs, the use of increased number of relatively low powered pumps has been investigated for DWDM system. The optimization of the pump powers has been evaluated in terms of signal degradation, gain, gain variation and OSNR. It has been demonstrated that a maximum gain of 45.38 dB for 96×40 Gbps, 25 GHz system is attainable up to 200 km of transmission distance while maintaining OSNR>18 dB using the proposed hybrid. No gain compensation or gain optimization technique has been used. The findings of this work establish flat gain in narrowband DWDM systems is achievable through proper optimization of pump wavelengths and their powers.