Characteristics and applications of intense coherent THz pulses from the NSLS SDL linac

The National Synchrotron Light Source (NSLS) Source Development Lab (SDL) operates a unique photo-injected linac capable of producing sub-picosecond electron bunches. The low frequency (THz) synchrotron radiation emitted by these bunches appears as half or single cycle coherent pulses. As previously demonstrated by others, the THz pulses can be coherently detected using the electro-optic effect in ZnTe. Our measurements reveal transient electric field strengths approaching 1 MV/cm for ∼100 microjoule pulses. Pulses of such intensity enable a variety of experimental studies where the THz pulses serve to excite a material rather than simply probe it. We describe a measurement where the THz pulses are used to drive a transient supercurrent in a superconductor such that the material´s critical current is exceeded.