Design and Performance analysis of High speed optical communication links

Abstract

In recent years, research in the field of lightwave communication has emerged to a completely next level. The optical communication has evolved as a viable solution to a high speed transmission systems owing to its higher bandwidth encompassing higher data rates. Use of advanced modulation formats which can support higher data rates with easier transmitter and receiver designs is one of the attractive solution to design the spectrally efficient high speed optical transmission links. This strategy also motivates the researchers and design engineers to further explore the capabilities of different modulation formats. In the recent past optical communication networks have been specifically engineered and optimized to support various communication standards exploiting the capabilities of fiber, integrated waveguides and related optical hardware, and signal conditioning circuits. The present thesis attempts to study, model, simulate and analyze the optical channel performance under various transmission conditions encountered in a practical high speed design. To improve the overall performance of the optical transmission links operating at 1550nm wavelength, this thesis focuses on mainly four approaches 1) channel capacity enhancement by reducing the fiber impairments through spectral management techniques, 2) improving the spectral efficiency by adopting robust pulse shaping and multilevel modulation techniques, 3) increasing the transmission capabilities with the use of multichannel WDM systems and 4)implementation of dispersion managed maps to maintain the nearly Gaussian shape of the propagating pulse for the long haul optical transmission links. Each of these methods has been implemented by addressing design challenges with an appropriate tradeoff. To start with the first approach, analysis of linear and nonlinear impairments in 40Gbps RZ-modulated Gaussian pulse propagation has been done. For this analysis, Gaussian pulses of different duty cycles are considered and the spectrum of these pulses is altered with