An optoelectronic adaptive resonance unit

The authors demonstrate a hardware implementation of the adaptive resonance theory ART 1 neural network architecture. The optoelectronic ART1 unit, is a novel application of an old device. This device-the 4-f or Van der Lugt correlator-has historically been used as a fast pattern classifier. Usually the correlation operation is employed as a matched filter, so that a maximum correlation peak corresponds to a well-matched pattern. The device described also uses the large peaks, but takes specific advantage of the fact that a zero-shift correlation is mathematically equivalent to a two-dimensional inner product. The authors describe a promising method for emulating an ART1 unit in optics. They review ART1 from an algorithmic point of view, which shows that inner products are a critical part of ART1. They then discuss its implementation, and show some experimental results. The device works by performing the most computationally intensive parts of the algorithm in optical hardware, and thus offers a suitable marriage of the strengths of electronics and optics