PERFORMANCE ANALYSIS OF A HIGH-SPEED DIGITAL FIBER OPTIC COMMUNICATION SYSTEM

Abstract

An intensity modulation/direct detection system with transmission bit rate of 2.4 Gb/S through a step-index single-mode fiber has been simulated by computer. Dynamic behaviour of large-signal direct modulated injection lasers has been modeled by numerical integration of semiconductor laser rate equations and the model suitable for computer aided analysis is used to describe the propagation of chirped optical pulses through the fiber. Since the Gaussian filter is a reasonable approximation to linear phase Bessel filters and raised cosine filter, the receiver filter has been taken to have a Gaussian response. Due to the successful development of optical amplifiers, intersymbol interference (ISI) imposes a dominant limit on bit rate and transmission distance in long-haul optical fiber communication systems. Since the non-linear cancellation techniques are difficult to be implemented practically, a soft-decision ISI cancellation technique has been employed. A pseudo-random binary data stream has been transmitted and from the received data stream, probability of error has been calculated.