Simple Code Switching Scheme for Security Enhancement of OCDMA Communication System

A simple code switching scheme for security enhancement of an optical code-division multiple-access (OCDMA) communication system is proposed. The scheme avoids the replacement of all the encoders and decoders in the system and all users' codes are changed by only tuning the center wavelength of the laser source. Each en/decoder contains multiple codes which are nonoverlapping in the spectrum. The scheme is demonstrated in a proof-of-principle transmission experiment. There are three codes on the encoder and decoder pairs, one 2-D code and two 1-D bipolar gold codes with chip number of 63 and 127, respectively. All three codes are decoded successfully after 12.7-km single-mode fiber link.