Optical codes with large cardinality and tree structures of multiple subsets of codewords for adjustable code performance and cardinality have recently been proposed. As studied in this paper, these characteristics support multicode-keying encryption for enhancing physical-layer confidentiality in optical code-division multiple-access systems and networks.
The concept of the multicode-keying encryption technique is introduced. The associated all-optical hardware is designed and validated with OptiSystem simulation. The theoretical analyses of confidentiality improvement by means of rapid codeword switching and multicode-keying encryption are formulated.