The characteristics of the optically induced bipolar terahertz (THz) radiation from biased semi-insulating GaAs photoconductive switches were investigated using a free-space electrooptic sampling technique. The emitted radiation shows a nearly symmetrical waveform with a broad-band frequency spectrum spanning over 0.1-3 THz, which displays essentially no dependence on the optical excitation fluence or strength of biased field. However, it does slightly depend on the emitter gap spacing. The dynamics of the emitted THz transient is in agreement with the optically induced ultrafast charge transport process driven by the biased field.
|Journal||Japanese Journal of Applied Physics, Part 2: Letters|
|Issue number||10 B|
|State||Published - 15 Oct 2002|
- Free-space electrooptic sampling
- Photoconductive switches
- THz radiation
- Ultrafast laser pulse illumination