Research
The PNP Research Group has focused on fundamental aspects of light-matter interaction at the nano-scale and new optical phenomena. Our group performs research in a variety of areas of microwave, terahertz, and optical electromagnetics science and technology.
Plasmonics
Surface plasmon polaritons, as the precise term would be, constitute an excitation where an electromagnetic field is coupled to the density oscillations of the conduction electrons in a metal. They share properties of the electromagnetic field as well as from the plasmon.
Basically, localized and propagating surface plasmon polaritons can be distinguished. They are either sustained at isolated metallic nanostructures or the extended interface between a metal and a dielectric, respectively. They allow to localize energy in spatial domains much smaller than the optical wavelength, they sustain huge electromagnetic fields, and they sustain a resonant response usually in a narrow frequency domain. In the mid-infrared region, Graphene can also support highly confined SPPs with long propagation lengths, compared to metal-based devices. We look into the strong field enhancement and light confinement to nano-scale volumes of plasmon modes, both in metallic and graphene-based structures in the THz frequencies.
Metamaterials
Metamaterials are a novel class of artificial materials that affect the properties of light by suitably chosen unit cells, called meta-atoms. A rough definition would define metamaterials as structures where the chosen geometry of the unit cells predominantly affects the properties of light. In a narrower definition, we would require that the meta-atoms are such small that the light effectively does not probe the isolated elements but rather perceives an effective medium. The properties of this effective medium in turn aredictated by the chosen meta-atoms and their arrangement. Metamaterials are at the heart of many groundbreaking applications, such as a perfect lens or a cloaking device that can hide objects from an external observer. They also constitute an excellent means to effectively tailor a nonlinear response or to change the local density of electromagnetic states.
Metasurfaces
Metasurfaces are a topic of significant research and are used in various applications due to their unique ability to manipulate electromagnetic waves in microwave and optical frequencies. These artificial sheet materials, which are usually composed of metallic patches or dielectric etchings in planar or multi-layer configurations with sub-wavelength thickness, have the advantages of light weight, ease of fabrication, and ability to control wave propagation both on the surface and in the surrounding free space.