Patent ID: 7542630

Claim:
An optical device, comprising: a phase modulator that includes a waveguide on a substrate, the waveguide having a light signal carrying region; an n-type region having a proximity to a p-type region that causes a depletion region to form when a bias is not applied to the modulator, the depletion region being at least partially positioned in the light signal carrying region of the waveguide; and the phase modulator includes a plurality of sub-modulators connected to a transmission line configured to carry a bias signal to each of the sub-modulators, the sub-modulators being spaced apart from one another along a length of the waveguide, the length of the sub-modulators along the waveguide and the spacing between the sub-modulators being selected such that the average speed of the bias signal through the transmission line is about the same as the average speed of a light signal traveling through the phase modulator.