Impact of analogue pre-filtering for spectral roll-off improvement in spectral efficient transmitter

Abstract

Spectral shaping plays a significant role in enabling high spectral efficiency of optical transmission systems. However, most of the spectral shaping methods reported so far have remained very complex using digital processing techniques that requires a large number of filter taps for optimal performance. In this paper, we show how the spectral roll-off factor can be reduced using a wavelength selective switch (WSS) at the transmitter side. We discuss the impact and limitations when using this method. The study investigates the practicalities of WSS generated optical filters at transmitter side via VPI simulations, evaluating the performance in terms of receiver sensitivity and BER.