High-security OCDM-PON system of 7-core fiber based on CFCM encryption

In this paper, we propose a high-security orthogonal chirped division multiplexing passive optical network (OCDM-PON) based on three-dimensional (3D) encryption, including the encryption of bitstream, constellation, and subcarriers. Cascaded fractional-order chaotic mapping (CFCM) is used to generate three masking factors to achieve ultra-high-security encryption in three different dimensions. Logistic mapping is used to control the order of the scheme, which effectively increases the key space to 10¹⁵² and improves the security performance of the system. The experiment proves the feasibility of the encryption scheme on OCDM after 16 orthogonal amplitude modulation (16QAM). The encrypted 16QAM-OCDM signal transmits data at a rate of 56 Gb/s on a 2-km 7-core optical fiber, and simultaneously transmits the 16QAM orthogonal frequency division multiplexing (OFDM) signal under the same conditions. It is shown that OCDM-PON is 1.3 dB higher than OFDM-PON in terms of receiver sensitivity when the bit error rate (BER) is 10^-3.