A family of Nyquist pulses for coherent optical communications

Abstract

A new family of Nyquist pulses for coherent optical single carrier systems is introduced and is shown to increase the nonlinearity tolerance of dual-polarization (DP)-QPSK and DP-16-QAM systems. Numerical investigations for a single-channel 28 Gbaud DP-16-QAM long-haul system without optical dispersion compensation indicate that the proposed pulse can increase the reach distance by 26% and 19%, for roll-off factors of 1 and 2, respectively. In multi-channel transmissions and for a roll-off factor of 1, a reach distance increase of 20% is reported. Experimental results for DP-QPSK and DP-16-QAM systems at 10 Gbaud confirm the superior nonlinearity tolerance of the proposed pulse.

Evolutionary Design of Pulse-Shaping FIR Filter to Mitigate Fiber Nonlinearity

“…Note that the Nyquist condition is not required since LEQ is used at the receiver to deal with channel ISI. This relaxation may give us a potential to compete with the other Nyquist-based filters [4][5][6][7][8]. For a (2L + 1)-tap symmetric FIR filter, we have at least L degrees of freedom to design.…”

“…The effect of pulse shaping in fiber-optic communications has been investigated in literature [1][2][3][4][5][6][7][8][9]. For example, it was shown [1][2][3] that reduced nonlinear interference (NLI) is achieved by using a return-to-zero (RZ) pulse.…”

“…Analogously, an impulsive Nyquist shape was designed numerically [4,5]. To further improve performance in wavelength division multiplexing (WDM), stair-case pulse [6] and root M-shaped pulse (RMP) [7,8] were proposed. It was verified [8] that the RMP performs better than the impulsive shape and root-raised-cosine (RRC) filter, leading to a reach extension by more than 11.7%.…”

Nyquist-WDM With Low-Complexity Joint Matched Filtering and Adaptive Equalization

“…Raised-cosine (RC) pulses are usually chosen to satisfy the Nyquist theorem [6]. In such systems, matched filtering can be exploited to provide the best performance [7], by implementing root-raised-cosine (RRC) filters at both the transmitter and receiver, to realize an overall RC spectral shape.…”

The study of fiber nonlinearity compensation effect based on mid-nonlinearity temporal inversion in CO-OFDM system

“…Better nonlinear performance could be obtained by using a 50% return-to-zero (RZ) pulse instead of a non return-to-zero (NRZ) pulse, nevertheless implying a reduced spectral efficiency at the same time [7]. By using the root-raised cosine (RRC) pulse, the spectral efficiency of optical coherent single carrier systems can be improved compared to systems using the NRZ pulse [8]. The pulse shape optimized to reduce the effect of fiber nonlinearities is the Nyqusit pulses specifically designed for coherent optical communications compared to RZ, NRZ and RRC pulses [9].…”