High powered half-cycle THz pulses

Summary form only given. We discuss the production, propagation, and applications of high powered unipolar subpicosecond electric field pulses produced in semiconductor photoconducting switches. The broad coherent bandwidth and high peak fields in these pulses have found applications in spectroscopy, in time-resolved studies of quantum wavepackets, and in control of quantum phenomena such as photoionization. These pulses propagate and reflect from metallic mirrors like light pulses, but they have some unique properties. For example, half-cycle pulses can exchange energy with free electrons, since the time-integrated electric field is non-zero. The pulses can also be shaped to provide light sources with properties not obtainable with other far-infrared devices.