The optimal testing in photonic switching networks using tabulation methodology

Abstract

Optical crosstalk, a problem commonly found in Dilated Optical Multistage Interconnection Networks (DOMINs), is the outcome of undesirable coupling within a 2×2 directional coupler. As widely recognized, a switch is faulty if it causes crosstalk in excess a given threshold, the value of which can be determined according to certain criteria. Diagnosing faulty switches, which includes detection and location procedures, has become an important issue for DOMINs. The fault cluster (or test set) is an independent set of tests for diagnosing faulty switches. The test patterns (or disjoint faults) in each fault cluster can be applied in parallel during diagnosis. The fault-table method is a classical analytic and deterministic minimization method used in the circuit testing of VLSI. The method is especially efficient when tackling complicated circuits, and can be solved efficiently by modern computer technology. An algorithm that uses the tabulation method is developed to obtain the optimal fault cluster(s) for both detection and location tests. The paths of the injected signal, output signal and faulty signal throughout the network are collected to determine the conflict table. Then, the conflict table is minimized to yield the fault clusters. The fault clusters are then stored in the management system. The results can help us to diagnose faulty switches in parallel to accelerate the diagnosis. The tabulation methodology follows the same diagnostic procedure for the various infrastructures and is independent of the size of the DOMINs. Furthermore, a computer program can simulate the procedure and the results support the optimal test.