I. Introduction
In a local-area network (LAN) environment where the traffic is usually bursty, an efficient multiple access protocol that allows many users to access the network asynchronously at all times is essential. Optical code-division multiple access (OCDMA) is a very attractive multi-access technique that can be used for this purpose. Many OCDMA strategies have been proposed for one-dimensional (1-D) optical coding [1]–[3], and more recently for two-dimensional (2-D) optical coding [4]–[6]. For LAN systems, the two most important parameters are the maximum number of users that can be supported and the bit error rate (BER) in terms of multi-access interference (MAI). Due to the unipolar characteristics of optical signals, which result from the combination of intensity modulation and direct detection (IM/DD), long 1-D codes have been developed to increase the number of simultaneous users. However, the systems that adopt those coding schemes suffer from poor system capacity and BER performance. 2-D codes are a possible solution to overcome these limitations.