3D-CAP-64 modulation based on hybrid geometric-probabilistic shaping using regular hexagonal cells in silicon photonic modulator IM/DD system

For the intensity modulation/direct detection (IM/DD) transmission system based on silicon-based Mach-Zehnder modulator, a three-dimensional carrier-less amplitude-phase modulation scheme (PS-3D-CAP-64-C H ) based on joint probabilistic shaping and geometric shaping using regular hexagonal cells is proposed. The bit error rate (BER) performance of the communication system is significantly improved while the transmit power is reduced. The PS-3D-CAP-64-C H signals at a rate of 26.4 Gb/s are successfully transmitted over a 5-km standard single-mode fiber. The results show that the receiver sensitivity of the proposed PS-3D-CAP-64-C H scheme is improved by 2.1 dB compared to the traditional uniformly distributed scheme at an information entropy of 5.8 bits/symbol and a BER of 3.8 × 10 −3 . Experimental results demonstrate that the proposed scheme has strong potential for future short-reach optical communication applications.