Fault avoidance for fixed-interconnect optical computers

Optical computers can be assembled by using fixed-interconnect structures to connect two-dimensional optical arrays. A four-phase model of the optical computer assembly is described, and the roles of design density (i.e., the number of available gates used in a design) and fault density and the assembly technique are empirically investigated. Low-cost array assignment techniques that make use of optical logic arrays with faulted gates and multiple-array orientations are introduced and shown to increase an effective yield by between 50 and 100%. These techniques provide near-optimal solutions to the general optimal array assignment problem, which is shown to belong to the complexity class NP-hard.