Performance Degradation of 100Gb/s PM-QPSK and 400 Gb/s PM-16QAM Coherent Communication Systems Due to Optical Filter Cascade and Chromatic Dispersion

Abstract

In the near future, data rates of 100 Gb/s and 400 Gb/s will be used to match the increase in bandwidth demand for capacity. Wavelength division multiplexing (WDM) systems transmit multiple wavelengths simultaneously at high data rates over long distances where the signal passes through multiple optical add drop multiplexers (OADMs) along the fiber link towards the destination. The transmitted signals su_er from dispersion induced from the fiber and OADMs, where these e_ects are an important limiting factor. The success of high-bit rate, long-haul, point-to-point optical transmission networks depends on the management of the fiber's linear and non-linear e_ects. In this thesis, we propose to study the impact of cascaded filters as the signals pass through multiple OADMs to determine its e_ect on the next generation network's data rates. We aim to study the impact of cascaded filters on single-carrier and dual-carrier 100 and 400 Gb/s optical transmission systems. The eye closure penalty (ECP) will be used as a performance evaluation metric. The results indicate that the filter cascade has a severe impact on the performance of dual-carrier systems relative to the case of single-carrier systems. Secondly, chromatic dispersion (CD) e_ect will be mitigated electronically for 100 and 400 Gb/s systems using fiber-dispersion finite impulse response (FD-FIR) filter. The compensating FIR filter's coe_cient will be computed from the impulse response of the inverse of the fiber's transfer function. Bit error rate (BER) versus optical signalto- noise ratio (OSNR) curve will be used to evaluate the compensating technique. The results indicate that for 100 Gb/s PM-QPSK systems, using 2 samples/symbol with maximum number of taps is the best approach to compensate for CD. While for 400 Gb/s PM-16QAM systems, using 4 samples/symbol with 50% of the maximum number of taps is the best approach to compensate for CD.