Focusing of Terahertz Waves onto Micron-sized Slits Grown on ZnTe and GaP Substrates

We report on terahertz focusing through rectangular slit apertures on thin metal film by using terahertz time domain spectroscopy both in the farand in the near-field. Our experiments show that far-field perfect transmission is maintained in the rectangular slit array even as the aperture coverage decreases. Near-field imaging supports the field enhancement in the single rectangular aperture indeed occurring at a frequency equal to the fundamental shape resonance frequency.