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All-dielectric Nano-photonics

There is a common belief, seemingly relying on seminal textbook of Landau and Lifshitz, that there is impossible to achieve magnetic responses at high, e.g. optical frequencies. The reasoning was microscopic and related to the nature of spin and orbital interactions of light with electrons – its inefficiency, in fact. Hence the permeability of optical materials is almost equal to 1.  However, it was recently shown, that multipole moments in particles made of high refractive index materials, e.g. silicon or germanium, could indeed exhibit magnetic properties. This discovery started the era of ‘All-dielectric Nanophotonics’, having the studies of novel types of light-matter interactions, light harvesting and concentration, novel type of magnetic metasurfaces, detection of magnetic transitions in atoms, and others as primary objectives. 

 

Figure 1 - Scheme of bianisotropic dimer where the spectral position of electric dipole resonance of one particle coincides with the spectral position of magnetic dipole resonance of another one. Corresponding dipoles spectra.

Our Lab investigates all-dielectric systems by applying approaches of configuring multipole spectrum of complex geometries. Effects of induced bi-anisotropy, enhancement of magnetic moments, and harvesting of magnetic fields and their concentration. Those basic building blocks are aimed to be employed for large scale metasurfaces for photo-voltaic applications.

Opto-mechanical tools could also contribute to development of all-dielectric devices. Multipole moments in particles could be utilized for directional scattering and, as the result, tailor characteristics of mechanical forces. For example, an interplay between electric and magnetic dipolar responses could lead to a unique beaming of scattered radiation. This additional flexibility in control of macroscopic structural responses was shown to enable above mentioned ‘tractor beams’, side control motion, levitation and others.