Symmetric 100 Gb/s CO-OFDM-PON with Massive Connectivity for Ultra-Dense Industrial Access Networks

Industrial automation and the Internet of Things (IoT) are driving demand for optical access networks capable of supporting massive connectivity with deterministic low latency. Conventional passive optical networks (PONs) face scalability and cost limitations in ultra-dense deployment scenarios. Here we propose and experimentally demonstrate a polarization-carrier dual-reuse coherent orthogonal frequency division multiplexing PON (CO-OFDM-PON) architecture enabled by optical frequency comb (OFC) sources. The design maps data and carrier signals onto orthogonal polarization states. This enables carrier reuse for both downstream coherent detection and upstream transmission through injection-locked laser (ILL)-based carrier regeneration at the optical network unit (ONU). We comprehensively characterize the key subsystems. These include the OFC, ILL, and erbium-doped fiber amplifier (EDFA). This ensures stable multi-wavelength generation, carrier regeneration, and enhanced receiver sensitivity under high split ratios. Through simulation and experimental analysis of fiber nonlinearities in industrial PON scenarios, we identify an optimal per-channel launch power of 4 dBm. This power balances sensitivity and link budget requirements. Scalability analysis for standard PON reach is also provided. The system demonstrates 16-channel 100 Gb/s per wavelength downstream 16-QAM OFDM transmission. The link budget exceeds 34 dB with bit error rates (BERs) below the forward error correction (FEC) threshold of 1 × 10−2. While the coherent ONU architecture offers superior spectral efficiency, it entails higher component costs than direct-detection alternatives due to the required coherent receiver and polarization management components.