Bidirectional Radio-Over-Fiber Systems Using Double-Clad Fibers for Optically Powered Remote Antenna Units

This paper shows and experimentally demonstrates bidirectional radio over fiber (RoF) using a double-clad fiber (DCF) for optically powered remote antenna units (RAUs). The DCF for an RoF link has a single mode (SM) core and a multimode inner cladding; the SM core is used for simultaneous downlink and uplink transmissions of the optical RoF data signals, whereas the inner cladding is used for optical power delivery to the RAU. The aim of this approach is to optically power the RAU in such a way that external electrical power supplies, such as batteries or public power lines, are not required. The feasibility of the technique is demonstrated by bidirectional RoF transmission over a 100-m DCF optically feeding with 4.0 W. We successfully achieved high downlink and uplink transmission performance in terms of error vector magnitude measurements, which are based on the IEEE 802.11g wireless local area network (WLAN) standard at a carrier frequency of 2.45 GHz.