A Self-Organizing Photorefractive Frequency Decoder,
COLORADO UNIV AT BOULDER DEPT OF PHYSICS
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We demonstrate a self-organizing photorefractive circuit which decodes optical signals. The circuit is a pair of ring resonators with photorefractive gain and cooperative and competitive mode interactions. When a spatially multimode beam containing two optical carrier frequencies is used as the pump, the resonator self-organizes such that each frequency oscillates in spatially separate rings. Initial results, with a two crystal BaTiO3 resonator, show a contrast ratio of better than 201 at the two outputs. Consider the circuit shown schematically. The photorefractive crystal in the center provides gain from a pump signal to two unidirectional, multi-mode ring resonators. Part of the energy in each ring is split off, and fed back into itself in a cooperative fashion by two beam coupling in a second photorefractive crystal. If the pump consists of a single optical frequency this configuration leads to a flip-flop behavior between the two resonators. This is similar to a previously reported flip-flop based on a competitive interaction between the rings. When the pump beam consists of two optical frequencies, in spatially orthogonal modes, the photorefractive gratings dynamically self-organize leading to a demultiplexing behavior.
- Electrical and Electronic Equipment