High-Permittivity All-Dielectric Nanoparticles: A Novel Low-Loss Platform for Nanophotonics

• Applicant: Professorin Dr. Isabelle Staude
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 279916641

This project aspires the development of a new platform for nanophotonics based on high-permittivity all-dielectric nanoparticles. Such nanoparticles support strong localized electric and magnetic multipolar optical resonances, whose properties can be tailored by the size, shape, and material composition of the nanoparticles. As such they can be utilized in direct analogy to plasmonic resonances of metallic nanoparticles to manipulate light-matter interactions at the nanoscale. However, in contrast to nanoplasmonic systems, which inherently suffer from strong losses, dielectric nanoparticles can be practically lossless. Thus, all-dielectric nanoparticle structures immediately outperform nanoplasmonic structures in efficiency in many linear-optical applications such as wavefront engineering. However, this project will go beyond this regime of passive, linear, continuous-wave optics and experimentally investigate the use of all-dielectric nanoparticle structures for tailoring nonlinear optical effects, dispersion, and emission phenomena. It will be organized in two streams reflecting these aspects.The first stream will investigate nonlinear effects in dielectric metasurfaces, providing resonant enhancement of the light-matter interaction and the capability to tailor this interaction by design. In comparison to plasmonic metasurfaces they can be pumped at higher intensities and they concentrate the near-fields inside the nonlinear dielectric material instead of at its surfaces, making the nonlinear response less dependent on difficult to control surface properties. A crucial opportunity furthermore arises from the multipolar nature of the nanoparticle resonances. By tailoring the multipolar response, this project aims to deliver fundamental new insights into the role of the magnetic and quadrupolar contributions to the nonlinear process. Furthermore, it will extend the concept of graded metasurfaces and designed meta-atoms to the nonlinear regime with the goal to obtain control of the directional and polarization properties of generated nonlinear waves.The second stream will realize dielectric nanoantennas coupled to nanoemitters. The low losses directly translate into high radiation efficiencies and high quantum efficiencies of the coupled system. In addition, the multipolar character of the resonances is again a key factor. On one hand, it enables unprecedented functionality, as multipolar interference will be used to achieve high directivity and polarization control in combination with high radiation efficiency. On the other hand it offers an experimental approach to investigating enhancement of the photonic density of states for higher-order optical transitions, such as magnetic dipole or electric quadrupole transitions, in the near-fields of tailored multipolar resonances.Silicon and compound semiconductors will be used as constituent materials, the latter pushing high-permittivity nanoparticles structures to visible wavelengths.

• DFG Programme: Independent Junior Research Groups
• Major Instrumentation: Inductively Coupled Plasma (ICP) etching system
• Instrumentation Group: 5180 Elektronen- und Ionenstrahl-Quellen und -Bearbeitungsgeräte