Self-Homodyne Digital-Analog Radio-over-Fiber Fronthaul: Principle, Architecture, and Prospects

The next-generation radio access network is envisioned to support ultra-wide bandwidth, be highly reliable, and with low-latency wireless signal delivery in mobile fronthaul. In this work, we introduce a high-capacity self-homodyne digital-analog radio-over-fiber fronthaul architecture employing multi-core fiber. By delivering the unmodulated local oscillator (LO) through one of the cores, the influence of laser phase noise can be eliminated after coherent beating provided optical path matching. We experimentally demonstrate a single-wavelength 23.6-Tb/s common public radio interface (CPRI)-equivalent rate supporting the 1024-QAM modulation format. The remote LO can also serve as the optical source for up-link transmission with an aligned central wavelength. Moreover, we characterize and discuss the impact of the optical path mismatch-induced phase noise and random polarization rotation of remote LO, respectively. Further directions and practical implementations of DA-RoF are discussed. The results reveal the potential to upgrade the future fronthaul in terms of capacity, fidelity, and simplicity.