Experimental spreading and despreading of the optical spectrum

An experimental realization of direct-sequence spreading and despreading of the optical spectrum using off-the-shelf electrooptic modulators is reported. This capability is required to implement a fiber-optic network originally devised by G. Foschini and G. Vannucci (1983). The network utilizes spread-spectrum techniques on the optical spectrum, together with coherent signal detection to accommodate a very large number of simultaneous users, for a total throughput measured in hundreds of Gb/s. The results obtained provide confidence that a network built around this idea would perform according to theoretical calculations. Coherent spectral spreading and despreading is thus established as a promising communication technique for fiber-optic systems