Optoelectronic data filter for selection and projection

Database processing, like the majority of nonnumerical applications, exhibits a high degree of functional parallelism but does not require complex operations; therefore it is amenable to optical solutions. The architecture of an optoelectronic filter that is capable of performing selection and projection operations on a two-dimensional data array in a relational database environment is presented. The system receives input from a parallel optical memory, one page at a time, and performs logic operations by using optoelectronic smart pixels based on heterostructure phototransistors and vertical-cavity surfaceemitting lasers. Combinations of AND and XOR gates are used to realize row-lcolumn masking and comparisons of input data against user-supplied search arguments. The main goal of the filter is to reduce the effective data rate between the highly parallel optical storage and the low input data rate conventional electronic computer, thus efficiently interfacing currently available photonic and electronic technologies.