OCDM-SDM optical transmission system based on Polar interleaved prefix-free code distribution matching probability amplitude shaping

In this paper, a novel orthogonal chirp division multiplexing (OCDM) and space division multiplexing (SDM) encrypted optical transmission system based on polar interleaved prefix-free code distribution matching (PCDM) probability amplitude shaping is proposed. The use of prefix-free code distribution matching in combination with interleaved system polar codes through Probabilistic Amplitude Shaping (PAS) produces a 16 Quadrature Amplitude Modulation (PS-16QAM) OCDM signal with non-uniform distribution. In the encoding process, a four-dimensional hyperchaotic model is used, with the resulting four chaotic sequences encrypting multiple dimensions of the system. To verify the performance of the system, the transmission of 70 Gb/s (7×10 Gb/s) encrypted OCDM signals over 2 km 7-core optical fiber is demonstrated experimentally. Experimental results show that the receiver sensitivity can be improved by more than 3dB compared to uniform-distributed signal transmission. It is also verified that the key space of the proposed encryption scheme can reach 10144. The results show that the proposed OCDM-SDM encryption optical transmission system based on polar interleaved prefix-free code distribution matching probability shaping has good bit error performance and anti-jamming ability, and has important application prospects in the future optical access network.