This paper proposes a novel architecture for coherent optical code-division multiple-access passive optical networks (OCDMA-PON). As optical spreading sequences, a recently introduced prime code family hereby referred to as double-padded modified prime code (DPMPC) has been employed and analyzed. The transceivers operate under homodyne dual-balanced detection scheme. For coherent modulation, binary phase-shift keying is employed where the phase is modulated by Mach–Zehnder external phase-modulator. The proposed architecture for optical network units and line terminals are also presented and analyzed. The network scalability of fiber link distances as well as bit-error rate, considering 1) fiber link noise e.g., amplifier spontaneous emission noise; 2) thermal noise; 3) photo-detectors' shot-noise; 4) relative intensity noise; and 5) mainly multiple-access interference, have been investigated. The results have indicated that this architecture can improve the network scalability, capacity and transmission performance, leading to the promising scheme for optical transport networks.
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