3 μm aperture probes for near-field terahertz transmission microscopy

The transmission of electromagnetic waves through a sub-wavelength aperture is described by Bethe's theory. This imposes severe limitations on using apertures smaller than similar to 1/100 of the wavelength for near-field microscopy at terahertz (THz) frequencies. Experimentally, we observe that the transmitted evanescent field within 1 mu m of the aperture deviates significantly from the Bethe dependence of E alpha a(3). Using this effect, we realized THz near-field probes incorporating 3 mu m apertures and we demonstrate transmission mode THz time-domain near-field imaging with spatial resolution of 3 mu m, corresponding to k/100 (at 1 THz). (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.