Transmissão ótica coerente em altas taxas com formato de modulação DP-QPSK utilizando pré-filtragem.

Abstract

This work approaches the theoretical description and implementation on simulation of optical prefiltering method in optical communication systems with coherent modulation format DPQPSK (Dual Polarization Quadrature Shift Keying). This technique was recently proposed and demonstrated experimentally and it's admittedly included in the state of the art of techniques for increasing the spectral efficiency of communication systems that use optical transmission at high bit rates. Through appropriate software simulations the harmful effects of intersymbol interference induced by optical filtering in system performance are shown. An algorithm is proposed for multisymbol decision to reduce the impact of filtering, taking advantage of memory that it induces in the sequences of bits. Finally, the performance results for a system with prefiltering, obtained through simulation using the multisymbol decision algorithm proposed, are presented. In this work the option to evaluate with more emphasis a system that uses the modulation format DP–QPSK was assumed. That is the default format defined for the future generation of systems operating at information rates of 100 Gb/s, main target of current research and development of the next generations of commercial optical transmission technology in the physical layer of highcapacity networks.