Tunable, bandwidth controllable source of THz radiation

Tunable radiation in the range from 0.1 to a few THz by the interaction of a superluminous photoconducting front with an electrostatic `frozen wave´ configuration in a semiconductor is reported. The interaction converts the energy contained in the `frozen wave´ into THz radiation, whose frequency depends on the energy in the laser pulse creating the superluminous front and the wavelength of the static wave. Use of two-photon absorption leads to a volume interaction, creating a superluminous photoconducting front. Tunability was achieved by varying the laser pulse energy from 0.1 to 1 mJ. Power scaling as a function of the electrostatic `frozen wave´ energy was obtained. The capability of the concept to act as a narrow or wideband, tunable and powerful THz source is demonstrated