Patent ID: 7965433

Claim:
An optical commutator switch, comprising a plurality of dual-output electro-optic modulators interconnected in a tiered arrangement wherein a first tier, having a single modulator arranged to receive an optical input signal, is optically coupled to a final tier having at least two final tier modulators arranged to output a plurality of optical signals derived from said optical input signal, and wherein the optical commutator switch further comprises a bias controller having: at least one optical signal power detector for measuring the optical power of signals output by said at least two final tier modulators; a controller for deriving, from only said measurements of optical power of signals output by said at least two final tier modulators, the average optical power of signals output from each of said plurality of modulators and for determining respective bias control signals for achieving and maintaining operation of said plurality of modulators substantially at their quadrature bias points; and a bias control signal generator for generating said respective bias control signals and for applying them to the respective modulators.