a semiconductor - based optical modulator is presented that includes a separate phase control section to adjust the amount of chirp present in the modulated output signal . at least one section is added to the modulator configuration and driven to create a pure “ phase ” signal that will is added to the output signal and modify the e iφ term inherent in the modulation function . the phase modulation control section may be located within the modulator itself , or may be disposed “ outside ” of the modulator on either the input waveguiding section or the output waveguiding section . the phase control section may be formed to comprise multiple segments , with the overall phase added to the propagating signal controlled by selecting the different segments to be energized to impart a phase delay to a signal propagating through the energized section .