Terahertz waveform synthesis via optical pulse shaping

We describe the principles of free-space terahertz waveform synthesis by using a programmable optical pulse shaper to drive a photoconducting dipole antenna. We illustrate this technique using several experimental examples, including manipulation of the amplitude and the phase of ultrafast terahertz waveforms as well as generation of ultrafast bit sequences at terahertz frequencies. We present a theory which accurately predicts the shapes of the terahertz waveforms produced in our experiments. In addition to the controllability of terahertz radiation, we have shown that optical pulse shaping can be used to avoid saturation of the terahertz field at high-peak power and increase generation efficiencies for terahertz radiations at selected, narrow-band frequencies.