Resonantly-enhanced single-aperture transmission for near-field probes

Many schemes have been investigated to overcome the low-throughput of a subwavelength aperture imposed by Bethe´s aperture theory, with important consequences for near-field imaging and excitation below the diffraction limit. Arrays and single holes flanked with gratings allow for enhanced transmission. Here we propose a new resonant enhancement phenomenon that significantly increases the aperture through-put and does not require an array or grating. This effect makes use of the high-impedance of the TM₁₁-mode close to cut-off, which is perfectly impedance-matched to the high-impedance aperture.