Patent ID: 8873896

Claim:
An electro-optical phase modulator comprising: a substrate of electro-optical material; a waveguide formed in the substrate comprising an input for receiving incoming light and an output for outputting data modulated light; a set of at least two electrodes disposed on the substrate for modulating the waveguide; ground lines disposed on the substrate relative to the set of electrodes; each electrode in the set forming a shifting line relative to the waveguide and comprising: a first end proximate to the input for receiving a sequential bit of a precoded digital data input signal, at least one interaction length proximate to the waveguide for causing modulation in the waveguide; at least one shifted length distal from the waveguide for avoiding causing modulation in any other waveguides; at least one transition length between an interaction length and a shifted length, for shifting the electrode away from or towards the waveguide; and a second end proximate to the output; at least one electrode of the set having a first interaction length proximate to the input that is shorter than a second interaction length of the same electrode; at any position along the waveguide, at most one interaction length is proximate to the waveguide and adjacent interaction lengths are driven by different electrodes; and each electrode having a modulation strength proportional to the sum of its interaction lengths, whereby a scaling ratio of the modulation strengths is equivalent to the geometric sequence 2 n−1 for n=1 to the number of electrodes in the set and whereby the modulation strengths of each electrode produce S21 electro-optical frequency responses that are approximately equal to each other, when shifted to account for the scaling ratio.