RoF/FSO System Based on a Monolithically Integrated Multi-Wavelength Transmitter

We propose and report the implementation of a hybrid radio-over-fiber (RoF)/ free-space optics (FSO) system employing a monolithically integrated multi-wavelength transmitter. In such system, a 20-MHz bandwidth M-QAM signal is transmitted over 12.5-km optical fiber fronthaul, followed by a 1.5-m FSO access. The overall system performance is estimated by means of root mean square error vector magnitude (EVMRMS), as a function of optical power and modulation indexes. Experimental results indicate a 160 Mbit/s throughput, accomplishing the 3GPP requirements with plenty of margins, demonstrating a proof-of-concept of the hybrid system applicability for fifth/sixth generations of mobile networks (5G/6G).