Patent ID: 8164819

Claim:
An apparatus, comprising: a phase-modulation device for phase-modulating a first optical carrier signal having a given phase, resulting in a phase-modulated optical signal whose phase differs from the first phase by a phase value which is controllable by one or more inputs to the device, the phase-modulation device comprising a plurality of electrodes configured to produce a plurality of discrete phase shifts on the first optical carrier signal based on the inputs, such that the phase value is based on a sum of the plurality of discrete phase shifts; and a combiner element for combining a second optical carrier signal having the given phase with the phase-modulated optical signal to provide a waveform whose amplitude varies with the phase value; wherein the phase-modulation device comprises a plurality of optical phase modulators arranged sequentially over an optical path configured to propagate the first optical carrier signal; and wherein at least one of the optical phase modulators comprise at least one of the electrodes.