Spatiotemporal Shaping of Terahertz Pulses

Abstract

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 frequency was tuned by changing the width of the slit; the slope of the cutoff transition was altered by changing the thickness of the screen. We measured the transmission function of the filters, using large-aperture photoconducting antennas to create and detect the incident and transmitted electric field. Our experimental results were in excellent agreement with the performed finite-difference time-domain simulations of the propagation of the pulse through the slit. When the screen thickness was greater than the slit width, the filter was well modeled by a short, planar waveguide. Using a simple transfer function, we accurately describe the sharp cutoff and dispersion of such a filter. © 1997 Optical Society of America Recently terahertz (THz) pulses have proved useful for a wide variety of applications, including far-infrared 1 / time-domain spectroscopy, 2 study and control of Rydberg atoms, 3 T-ray imaging of optically opaque materials, 4 and impulse-ranging studies. 5 Applications exploit the features of THz pulses that distinguish them from optical pulses, namely their broad bandwidth and long center wavelength. The broad bandwidth allows for the exciting possibility for sculpting the pulses to meet a desired goal by modifying their spectra. Although shaped THz pulses have been made by modifying the optical pump intensity profile 6 or by manufacturing more complex emitters, 7 there are