Exogenous tone dither rejection in optical switching

摘要

Methods and apparatus for dither control of a micromirror using a servo control loop in an optical switching apparatus, an optical switching apparatus and optical network are disclosed. A servo control loop may use dither tone having two or more frequency components to dither an output driver that controls the position of a micromirror in an optical switch. The two components may be demodulated from an optical signal deflected by the micromirror. The optical signal may be fed into two band-pass filters. Each band-pass filter may have a pass band centered on a different one of the two frequency components. The envelope detector may compare the envelopes of the band-pass filter outputs. If the envelopes differ by more than a set threshold the output of the envelope detector may be forced to zero. Otherwise, the output of the envelope detector may be the sum of the two band-pass filter outputs.