I. Introduction
Optical code-division-multiplexing (OCDM) techniques are currently receiving much research interest due to their unique features of providing flexible asynchronous interconnections between a large number of active users in high bit-rate local access networks [1]. Many different coding techniques have been proposed in time and frequency domains, and recently multicode OCDM has been demonstrated to increase the transmission data rate, the spectral efficiency, and the system confidentiality [2]–[4]. In this scheme, bits are encoded into codewords, so that if users access the network, at least encoder/decoders (E/Ds) are required [5].