Code sequence recognition scheme based on differential detection to investigate the security of communication systems using multiple optical codes

In this paper we propose a scheme to compare any two encoded optical signals by using differential detection and identify optical code sequence in the encoded data stream. Furthermore, we propose an algorithm to recover the original data from the derived optical code sequence. This scheme can be used to analyze the security performance of multi-optical-code based secure optical communication systems such as M-ary code-shift keying optical code-division multiple access system (OCDMA) and four-state data encoding OCDMA system.