Dispersion Reduction Technique Using Subcarrier Multiplexing

We have developed a novel dispersion-reduction technique using subcarrier multiplexing (SCM) which permits the transmission of multiple 2.5 Gbit/s data channels over hundreds of kilometers of conventional fiber-optic cable with negligible dispersion. Using a lithium niobate external modulator having a modulation bandwidth of 20 GHz, we are able to multiplex several highspeed data channels at a single wavelength. At the receiving end, we demultiplex the data and detect each channel using a 2-GHz bandwidth optical detector. All of the hardware in our system consists of off-theshelf components and can be integrated to reduce the overall cost. We demonstrated our dispersion-reduction technique in a recent field trial by transmitting two 2.5 Gbit/s data channels over 90 km of commercially-installed singlemode fiber, followed by 210 km of spooled fiber. For comparison, we substituted the 300 km of fiber with eqdvalent optical attenuation. We also ian computer simulations to evaluate link behavior. Technical details and field trial results will be presented.