We investigate light-matter interaction on structured surfaces in a broad range of frequencies, from the visible to the THz (far-infrared). For this research we simulate, fabricate and characterize resonant structures with unique properties that we can control. This research can be classified within the topics nanophotonics and THz-photonics.
The field of nanophotonics studies the generation, propagation, manipulation and detection of visible and near-IR light in length scales comparable to or smaller than the wavelength of light and in ultrafast time scales. In the Surface Photonics group, we focus on arrays of metallic nanoparticles supporting collective plasmonic resonances. In particular, we study the absorption and emission of quantum emitters such as organic molecules and 2D semiconductors coupled to collective resonances. These resonances are interesting because of the very large electromagnetic field enhancement over relative large volumes, which makes them relevant for applications in, e.g., solid-state lighting and sensing. We are interested in the strong coupling regime in which Plasmon-Exciton-Polaritons (PEPs), i.e., hybrid light-matter quasi-particles, emerge when the coupling strength is sufficiently large.
THz radiation is electromagnetic radiation with a frequency in the range between microwaves and mid-IR. Resonant structures at THz frequencies formed by semiconductors or metals can control the propagation and enhancement of THz radiation. These structures respond to incident radiation depending on their orientation and shape. The far- and near-field of THz radiation can be strongly modified by resonant structures, leading to enhanced or reduced extinction and to large local electromagnetic fields. In the Surface Photonics group, we study these interactions both in the far- and near-field, using THz time-domain spectroscopy and microscopy. Our goal is to tailor THz fields with subwavelength precision and to use these fields for THz spectroscopy. Optical pump-THz probe spectroscopic techniques enables the contact-free determination of the photoconductivity and carrier dynamics of materials. Therefore, we use these techniques to investigate materials relevant for opto-electronic applications.