Patent ID: 7466877

Claim:
An alignment monitor operable to monitor modulation alignment variation of a plurality of optical modulators, comprising: an input fiber operable to: receive an optical signal comprising a plurality of photons, the optical signal modulated by a plurality of optical modulators, the plurality of optical modulators driven by a plurality of drive signals; a photon detector comprising a photon reactive material operable to: produce a reaction in response to the arrival of a predetermined number of photons, photons, a band gap energy of the photon reactive material being greater than or equal to a photon energy and less than or equal to two times the photon energy; receive the plurality of photons of the optical signal; produce a plurality of reactions in response to the arrival of the plurality of photons; and generate feedback in response to the plurality of reactions, the feedback reflecting the waveform of the optical signal, the feedback indicating modulation alignment variation among the plurality of optical modulators, the modulation alignment variation indicating a change in a relative delay between the plurality of drive signals; and a modulator driver operable to: receive a detector signal reflecting the feedback; and adjust at least one of the plurality of optical modulators in accordance with the feedback to compensate for weaker modulation alignment.