Two-way free-space optics-based interface between fibre and 5G communication employing polarisation-orthogonal modulation

Fifth-generation (5G) communication provides a substantial increase in data transmission capacity because of more available bandwidth and advanced communication techniques. It opens the door to a range of new applications, such as 4K/8K video streaming, Internet of Things, autonomous vehicles, unmanned aerial vehicles, and more. However, atmospheric attenuation poses a technical challenge for 5G communication, especially at higher frequencies. Free-space optics (FSO)-based interface between fibre and 5G communication integrates fibre optics, FSO and 5G communications, achieving high-speed and long-distance transmission and providing an alternative for 5G signal transport. Here we report a two-way fibre-FSO-5G wireless communication employing polarisation-orthogonal modulation. After 25-km single-mode fibre, 1-km FSO, and 20-m (millimetre-wave)/10-m (sub-6 GHz) radio-frequency wireless transport, satisfactorily low bit error rates and error vector magnitudes are acquired, meeting the demands of 5G emerging applications.