0.55 Tb/s heterogeneous Nyquist-WDM superchannel using different polarization multiplexed subcarriers

This paper depicts the design of 0.55 Tb/s heterogeneous Flexi-rate Nyquist-wavelength division multiplexed (Nyquist-WDM) Superchannel. Here, for the first time, four subcarriers of different modulation formats are accommodated, namely polarization multiplexed-binary phase-shift keying, polarization multiplexed-quadrature phase-shift keying (PM-QPSK), polarization multiplexed-8-quadrature amplitude modulation and PM-16QAM, each with 27.75 Gbaud symbol rate. The system transmission performance with acceptable bit error rate (BER) 4 × 10−3 is analyzed over pure silica core fiber (PSCF) in the presence of hybrid optical amplification, i.e., Raman amplifier along with a counter-propagating pump and Erbium-doped fiber amplifier. The presence of this hybrid optical amplification unit results in a limited optical signal-to-noise ratio requirement and makes the whole system cost-effective. The proposed work delivers excellent spectral efficiency of 4.5 b/s/Hz and highest transmission reach of 5500 km for PM-QPSK subcarrier and 2300 km for PM-16QAM subcarrier in the presence of PSCF. The system performance against intersymbol interference and noise is also analyzed with the aid of eye pattern plot at a minimum and maximum transmission length.