Even as the spread of wavelength-division multiplexing brings higher transmission rates along the miles of fiberoptic networks, a bottleneck still exists in getting data from the network to individual buildings. One solution is to take the signals being sent along the fiber and transmit them by radio. Researchers at Communication Research Laboratory (Tokyo, Japan) tested a system that uses an electroabsorption transceiver (EAT) and an optical add-drop multiplexer (OADM) to link 156-Mbit/s, 60-GHz radio signals to a fiber ring.
The setup includes a central station in which all light sources are contained and are multiplexed and amplified for downlinking and uplinking. Additionally, there is a series of base stations, each containing an EAT and an OADM. From the central station, modulated downlink channels (C-band) and continuous-wave uplink channels (L-band) are fed into the fiber backbone of the ring network. At each base station, a pair of C- and L-band wavelengths is dropped through an OADM to the EAT, which simultaneously detects and modulates the down- and uplink channels. Modulated L-band channels are added to the backbone again and sent back to the central station, where they are demultiplexed and detected. For more information, contact Toshiaki Kuri at firstname.lastname@example.org.