Integrated optical frequency comb for 5G NR Xhauls

We experimentally demonstrate the use of optical frequency combs (OFCs), generated by a photonic integrated circuit (PIC), in a flexible optical distribution network based on fiber-optics and free-space optics (FSOs) links, aimed at the fifth generation of mobile network (5G) Xhauls. The Indium Phosphide (InP) monolithically integrated OFC is based on cascaded optical modulators and is broadly tunable in terms of operating wavelength and frequency spacing. Particularly, our approach relies on applying the PIC in a centralized radio access network (C-RAN) architecture, with the purpose of optically generating two low-phase noise mm-waves signals for simultaneously enabling a 12.5-km of single-mode fiber (SMF) fronthaul and a 12.5-km SMF midhaul, followed by a 10-m long FSO fronthaul link. Moreover, the demonstrator contemplates two 10-m reach 5G wireless access networks operating in the 26 GHz band, i.e. over the frequency range 2 (FR2) from the 5G NR standard. The proposed integrated OFC-based 5G system performance is in accordance to the 3rd Generation Partnership Project (3GPP) Release 15 requirements, achieving a total wireless throughput of 900 Mbit/s.