A two-level process for diagnosing crosstalk in photonic Dilated Benes Networks

A two-level process for diagnosing crosstalk in photonic Dilated Benes Networks (DBNs) is presented. At level one is the Test-All-Switches (TAS) procedure, which obtains the crosstalk ratios of each and every switch in an N × N DBN in 4N tests using O(N · log² N) calculations. One of its applications is to identify single or multiple crosstalk-faulty switches in the DBN which generate excessive crosstalk. To reduce the number of tests and amount of computation when diagnosing only a few switches suspected of crosstalk-faulty along an arbitrary path, the Test-One-Path (TOP) procedure at level two is proposed. A recursive algorithm applicable to both procedures is used to configure the DBN for each test such that the necessary power measurements of the signals can be taken accurately. An important feature of the proposed diagnostic process is its suitability for automated test generation.