US Patent 9485552 Optical switch fabric with bias control

Methods and systems for bias control in an optical switch fabric include monitoring optical power at outputs of a plurality of switch elements in an N×N switch fabric that has N inputs, N outputs, and M≧2 stages. A bias control of a first of the plurality of switch elements is adjusted. It is determined whether the optical power at the outputs of the first switch element after bias control adjustment conform more closely to a predetermined criterion relative to the monitored optical power at the outputs of the first switch element prior to adjustment. The adjusting and determining steps are repeated for each of the remainder of the plurality of switch elements.