A Colorless Remote Antenna Unit for Bidirectional Photonic Antenna Remoting

A colorless (wavelength-independent) remote antenna unit (RAU) for bidirectional photonic antenna remoting is proposed and demonstrated, which is based on a reflective semiconductor optical amplifier electroabsorption modulator (SOA-EAM). Due to the gain saturation effect in the semiconductor optical amplifier (SOA) of the reflective SOA-EAM, the microwave signal carried by the downlink optical signal is received and effectively erased. Then, the electroabsorption modulator (EAM) converts the uplink RF signal to an optical signal, which is reflected back to the center office (CO) by the high-reflection coated facet of the device to provide the uplink service. No signal downconversion is needed since the modulation bandwidth of the EAM can reach tens of GHz. A proof-of-concept experiment is carried out. The RAU performs well in a bidirectional radio over fiber (ROF) system for providing 500 Mb/s wireless services centered at 2 GHz.