Security-Enhanced 3D-CAP-PON Based on Two-Stage Spherical Constellation Masking

A security-enhanced three-dimensional carrier-less amplitude phase passive optical network (3D-CAP-PON) based on two-stage spherical constellation masking is proposed in this paper, where Chua's circuit map and one-dimensional Logistic map are jointly applied to implement rotation-based and scaling-based 3D-constellation masking. The rotation masking converts the constellation into two spherical layers with different radii, while the scaling masking leads to a hollow sphere with thick wall. The dimensional expansion of the constellation, combined with the joint adoption of two chaotic models, enable more flexibility and security for constellation encryption. And the key space of the proposed scheme is 1.2times 10{73} when taking only initial values and step lengths of chaotic models into consideration. A 4 Gb/s encrypted 3D-CAP-16 signal transmission over 25 km standard single mode fiber (SSMF) is experimentally demonstrated. The experimental results indicate that the proposed scheme can effectively protect the system from any illegal optical network unit (ONU) attack, proving to be a promising candidate for future physically secure 3D-CAP-PON.