Bit Error Rate Performance Analysis of an Optical Fiber Communication System with a Multi-Core Fiber

Abstract

Multicore Fiber (MCF) is found to be a promising candidate to replace Single Mode Fiber (SMF) in order to increase the capacity of an optical fiber link. In this thesis, investigations are carried out to find out the limitations imposed by crosstalk due to coupling between the cores of an MCF on the Bit Error Rate (BER) performance of a MCF optical link. Analysis is carried out for single mode multicore fiber (MCF) to find the electric fields and power induced from one fiber to another for a given structure of a MCF, number of cores, refractive index profile etc. The expressions of the signal power at the output of the different cores of the MCF with excitation to any one of the cores is found out along with the crosstalk. The expression for the crosstalk power due to coupling among the cores is also determined. The analysis is extended to optical MCF link with an optical pre-amplifier followed by direct detection receiver. Finally, the expression for Signal to Crosstalk plus Noise Ratio (SCNR) at the output of the excited fiber core is found. Computations are carried out for signal power of the desired channel and crosstalk power due to other channels. The BER for a given data rate is then determined numerically for different MCF parameters and transmission distance. The optimum system design parameters like coupling co-efficient between cores of MCF, BER, transmission distance, input power range, gain of the optical pre-amplifier etc, is determined for a given data rate. The outcome of this research work will be useful to design fiber optic system with Multi-core single-mode fiber running at BER comparable to multi-mode fiber links. The proposed system may be a potential candidate for future MIMO fiber optic communication system.