Patent ID: 6917455

Claim:
An optical modulator architecture, for use in an optical communication system, comprising: a multiple optical modulator arrangement including a pair of optical modulators coupled in cascade in the output light path of a laser, wherein a first optical modulator has a return-to-zero RZ RF signal modulation port to which a sinusoidal RF clock signal from a narrowband modulator driver is coupled, and a DC bias port to which a DC bias therefor is coupled, and wherein a second optical modulator optically has a non-return-to-zero (NRZ) RF signal modulation port to which an NRZ signal from a broadband modulator driver is coupled, and a DC bias port to which a DC bias therefor is coupled; an optical detector coupled to monitor composite NRZ-RZ modulated light produced by said multiple optical modulator arrangement; and a modulator bias control circuit which is operative to impress dithering signal modulation upon said NRZ-RZ modulated light, and to control bias points of the modulators and phase delay of an electrical phase shifter in a manner that aligns the phase of said optical RZ signal with that of said optical NRZ signal, based upon detected dither signal energy in an output of said optical detector.