All-optical phase control of THz waveforms

We demonstrate all-optical broadband phase control of THz pulses. By spatially patterning a fs pump pulse we inject photoconductive regions inside a silicon-filled THz parallel-plate waveguide (PPWG), defining light-induced THz quasi-optical components within the waveguide. We show carrier envelope phase shifts of single-cycle THz pulses as well as synthesis of chirped waveforms, including a negative chirp of -11 GHz/ps between 0.3 and 0.5 THz.