THz Near-field spectroscopy of metamaterial resonators

Terahertz near-field spectroscopy is a powerful technique for the investigation of metamaterial resonators with subwavelength resolution. Here, we used an a-SNOM THz time domain spectroscopic system for the direct study of all the modes supported by individual D-split ring resonators, their E-field distributions and relative Q factors. A cross-polarized excitation and detection technique is also demonstrated, yielding a modes’ mapping by the resonators with unprecedented resolution and sharpness.