Constellation-designed 32QAM with geometric and probabilistic shaping for optical fiber system

A constellation-designed 32QAM method is proposed using geometric shaping (GS) and probabilistic shaping (PS). In addition, a 50-Gbaud polarization division multiplexed multispan optical fiber link for the proposed scheme is set up. The simulation results show that when the net data rate reaches 211 Gbit/s, the proposed 32QAM with GS and PS is capable of achieving about 0.1- A nd 0.3-dB OSNR gain over PS-32QAM and regular 32QAM (R-32QAM), respectively. When 213 Gbit/s net data rate transmission is achieved, the use of the proposed 32QAM can increase the transmission length by ∼60 km over PS-32QAM and ∼210 km over R-32QAM. Moreover, when OSNR is set to 19 dB and signal bandwidth is 40 Gbaud, the net data rate of the proposed 32QAM is 2 and 7.5 Gbit/s larger than PS-32QAM and R-32QAM, respectively.