Self-organizing photorefractive frequency demultiplexer.

We demonstrate a self-organizing photorefractive circuit that demultiplexes a beam that has two signals imposed on separate optical carrier frequencies into two beams, each containing one of the signals on its carrier. Unlike conventional demultiplexing techniques, this method requires little a priori knowledge about the carrier frequencies. The signal channels must be spatially uncorrelated, and their frequency separation must be more than the photorefractive response bandwidth (hertz to kilohertz). The optical circuit uses no local oscillator, and the photorefractive response bandwidth places no upper bound on the channel bandwidth. Experimental results for demultiplexing a beam that has two signals, with a BaTiO(3) circuit, show contrast ratios of better than 40:1 at the outputs.