Terahertz pulse propagation through small apertures

Propagation 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 law show that the conventional d sup 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 the near-field probes allows achieving spatial resolution of 7 mu m for pulses with a broad spectral content of lambda =120-1500 mu m.