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.