FBG dispersion compensation in a 43 Gbit/s WDM system: Comparing different FBG types and modulation formats

Within this contribution the impact of phase ripples and amplitude filtering induced by fiber Bragg gratings (FBGs) for in-line dispersion compensation in optical long-haul wavelength division multiplex (WDM) transmission systems is investigated. The goal is to evaluate the possibilities and limitations of employing FBGs instead of dispersion compensating fiber (DCF) in modern communication systems with certain upgrade issues. The considered upgrade scenarios contain the increase of the data rate from 10.7 Gbit/s to 43 Gbit/s and employment of other modulation formats than conventional NRZ-ASK (non-return-to-zero amplitude shift keying), such as optical duobinary (ODB) and differential phase shift keying (DPSK). Moreover, the performance of channelized FBGs and broadband FBGs is compared for these scenarios. Since the FBGs' frequency and phase responses include stochastical components the investigations are performed by extensive statistical simulations. These simulations are based on measured group delay and insertion loss characteristics of numerous FBG samples. The results show performance limitations for channelized FBGs due to amplitude filtering and strong phase ripples at pass band edges, especially if ASK or DPSK modulation is applied. The broadband FBG offers significantly better transmission characteristics.