Patent ID: 7519249

Claim:
A semiconductor optical modulator comprising: a Mach-Zehnder device including two arms; and at least two optical resonators optically coupled to the arms of the Mach-Zehnder device, wherein each of the arms of the Mach-Zehnder device is coupled to at least one of the resonators; wherein each of the resonators exhibit a particular resonance frequency; and a plurality of phase shifters, wherein at least one of said plurality of phase shifters is positioned within each arm of the Mach Zehnder device and alters the optical coupling ratio between each arm and the corresponding resonator, and at least one of said plurality of phase shifters positioned within each one of the resonators tunes the respective resonance frequency, wherein upon simultaneously altering one or more of the coupling ratios and tuning the respective resonance frequencies, the resonance frequencies substantially overlap one another such that the modulator is turned to an ‘on state’ exhibiting a desired phase modulation, such that the modulator operates in two ‘on states’ exhibiting a ‘0’ or a ‘π’ phase shift between the ‘on states’, such that the modulator modulates an input signal according to a format selected from the group consisting of differential phase shift keying (DPSK), differential quadrature phase shift keying (DQPSK), phase amplitude modulation (PAM), duobinary, and their higher order embodiments.