Using 2‑D Doerite Codes with Two‑Code Keying for Polarization in an Optical CDMA System

We propose and demonstrate a new family of two-dimensional (2D) codes, termed “Doerite codes,” which are uniquely combined with a two-code keying (TCK) scheme that leverages two mutually orthogonal states of polarization (SOPs). This paper aims to overcome these limitations by introducing a novel, high-performance coding and system architecture for spectral amplitude coding optical code division multiple access (SAC-OCDMA). A comprehensive system architecture is designed, including a simplified optical line terminal (OLT) with a single transmitter and a dedicated optical network unit (ONU) structure that performs a modified correlation operation to effectively cancel multi-user interference (MUI) and suppress phase-induced intensity noise (PIIN). Numerical analysis based on our proposed system shows that it can support up to 660 simultaneous users at a bit‑error rate (BER) of 10−9. Furthermore, it achieves a maximum data transmission rate of 11.62 Gbps and requires a received source power of only −17.58 dBm. The innovative polarization, spectral, and spatial domains through TCK provide superior interference mitigation. These results demonstrate the significant potential of the proposed 2-D Doerite codes with TCK to enable high-capacity, high-speed, and power-efficient SAC-OCDMA systems for next-generation optical access networks.