Colloquia

Near-field microscopy has been proven to be a powerful technique for investigating the interaction of electromagnetic waves and matter at subwavelength scales. In this presentation, I will present an in-house developed THz double near-field probe microscope that allows near-field coupling and detection of picosecond THz pulses. The amplitude and phase near-field detection of THz radiation enables the spatial mapping of fundamental electrodynamic properties, such as spatial coherence, the local density of optical states, or energy transfer between dipoles. Using this microscope, we investigate symmetry-protected bound states in metasurfaces that cannot couple to radiation and are thus invisible in the far field. These bound states define perfect optical cavities, which makes them extremely interesting for applications in sensing, non-linear optics, and for enhancing light-matter interaction.