Performance Comparison of Bessel and Gaussian Optical Filters for Pulse Shaping and as a Mux-Demux Filter for DP-QPSK WDM Systems

Optical filter based devices are one of the important components of a wavelength division multiplexing (WDM) system. Optical filters are used to combine different channels (multiplexing) and to select a particular wavelength channel (demultiplexing). It is also used to shape the spectrum of optical signals. In this paper, we have compared the pulse shaping characteristics of Gaussian and Bessel optical filters for a 112 Gb/s dual polarization quadrature phase shift keying (DP-QPSK) WDM system. The comparison is done in terms of optical spectrum and time domain representation of DP-QPSK signals. We have also investigated the effect of filter shape (order of the filter) on the performance of the DP-QPSK WDM system. The multiplexing and demultiplexing characteristics of both the filters are also compared. The results indicate that Gaussian optical filter provide better performance as a pulse shaping filter as well as mux-demux filter.