FITD Simulation of Terahertz Near-Field Microscopes

The spatial resolutions of conventional THz TDS systems are limited by diffraction. In this work, we present a numerical analysis of apertureless THz pulse near-field microscopy (NFM), and successfully demonstrate that the THz NFM can have nanometer-scale resolution. For the numerical analysis we used CST MWS, a commercial software based on finite integral time domain (FITD) method. It is found that the THz near field is strongly localized around the probe tip as expected, which is of importance for nanometer resolution.