Terahertz pulse propagation through small apertures

Transmission of single-cycle terahertz pulses through subwavelength apertures is experimentally studied in the near-field zone. Measurements of throughput for aperture sizes d as small as lambda /300 show that the theoretical d(3) law requires a correction term which takes into account the physical thickness of the aperture screen. Frequency dependent transmission of the broad band pulses explains changes in their spectral and temporal characteristics. Practical application of small apertures in near-field microscope probes allows achievement of spatial resolution of 7 mum for pulses with a broad spectral content of lambda =120-1500 mum. (C) 2001 American Institute of Physics.