Converging fixed and mobile optical access networks for next-generation broadband services

Network convergence across fixed, mobile, and Wi-Fi domains will be a key requirement for sixth-generation networks, as it enables more efficient utilization of shared infrastructure and spectrum resources. In this paper, we experimentally demonstrate a converged fixed and mobile optical access architecture based on an amplitude–phase layered modulation scheme. By fully exploiting the modulation degrees of freedom of light, the amplitude dimension carries digital traffic that can coexist with services such as passive optical networks, the common public radio interface (CPRI), and enhanced CPRI, while the phase dimension transports analog radio signals for next-generation, high-fidelity, signal-to-noise ratio (SNR)-adaptive fronthaul and indoor mmWave applications. We achieve 100 Gb/s four-level pulse-amplitude modulation transmission over 20 km of standard single-mode fiber while simultaneously conveying wireless signals ranging from 11.72 GHz 64-ary quadrature amplitude modulation (64-QAM) to 0.58 GHz 65536-QAM with up to 53 dB SNR. In addition, the scheme is validated over a 40.4 km field-deployed fiber link, where 72 Gb/s on–off keying transmission is realized with wireless signals from 9.4 GHz 64-QAM to 0.58 GHz 65536-QAM. These results highlight the potential of the proposed approach to unlock the capacity of current and future fiber infrastructures by unifying fixed and mobile access within a single, scalable framework that also simplifies network deployment.