PHOTOSURF

Metasurfaces are ultrathin artificial materials composed of periodically arranged structural elements at a subwavelength scale.

They promise to revolutionize the interaction between light and matter, offering new possibilities that cannot be achieved with natural materials (such as anomalous refraction, high and near-zero magnetic permeability, etc.), by exploiting the electromagnetic resonances of their constituent elements.

At the same time, they are extremely thin compared to the wavelength and can be fabricated using conventional planar technologies.

However, there are certain physical limitations that restrict the potential of metasurfaces:

(i) their spectral response is typically narrowband, and

(ii) the phase delay imparted to the incident wave is limited (less than 2π).

The proposed research aims to overcome these long-standing limitations by appropriately combining multiple resonances within the unit cell of the metasurface. The proposed broadband multiresonant metasurfaces combine the advantages of sharp resonances (phase delay, energy storage, field enhancement) with an arbitrarily wide spectral bandwidth.

Maintaining broadband response as a common foundation, PHOTOSURF will address different physical problems through a unified approach. The central goal is to replace conventional bulky photonic components for dispersion, diffraction, polarization, and nonlinearity control with ultrathin counterparts, thereby offering significant technological advantages (in size, weight, fabrication, and integration).

In all cases, we begin with the rigorous mathematical determination of the electric and magnetic susceptibilities, propose physical implementations that satisfy them, and proceed to the experimental validation of the most efficient structures. The described scientific advances are expected to introduce metasurfaces into practical photonic applications involving broadband signals.