Measurement of spatio-temporal terahertz field distribution by using chirped pulse technology

The authors report the use of an optoelectronic system for the measurement of terahertz (THz) pulses by using chirped pulse technology. This system me asures the spatio-temporal distribution of free-space pulsed radiation with an unprecedented data acquisition rate. Using a linearly chirped optical p robe pulse with an electro-optic crystal, a temporal waveform of a copropag ating THz field is linearly encoded onto the frequency spectrum of the opti cal probe pulse and then decoded by dispersing the probe beam from a gratin g to a detector array. Acquisition of picosecond THz field pulses without u sing mechanical time-delay devices have been achieved. A single-shot electr o-optic measurement of the temporal waveform of a THz pulse has been demons trated. Unparalleled-by other THz sampling techniques, this single-shot met hod provides what is believed to be the highest possible data-acquisition r ate. Temporal resolution, sensitivity, optimal optical bias point of electr o-optic modulation, potential applications, and possible improvements are a lso discussed, In principle, this technique can also be used in magneto-opt ic measurements.