SPATIOTEMPORAL SHAPING OF TERAHERTZ PULSES

We report temporal shaping of few-cycle terahertz pulses, using a slit in a conductive screen as a high-pass filter. The filter's cutoff fre quency was tuned by changing the width of the slit; the slope of the c utoff transition was altered by changing the thickness of the screen. We measured the transmission function of the filters, using large-aper ture photoconducting antennas to create and detect the incident and tr ansmitted electric field. Our experimental results were in excellent a greement with the performed finite-difference time-domain simulations of the propagation of the pulse through the slit. When the screen thic kness was greater than the slit width, the filter was well modeled by a short, planar waveguide. Using a simple transfer function, we accura tely describe the sharp cutoff and dispersion of such a filter. (C) 19 97 Optical Society of America.