Enhanced chiroptical activity with slotted high refractive index dielectric nanodisks

Unveiling dipolar spectral regimes of large dielectric Mie spheres from helicity conservation

“…Notably, when the electric and magnetic polarizabilities of the scatterer are identical, at the so-called first Kerker condition [7], the EM helicity is preserved [8][9][10] and the intensity in the backscattering direction is exactly zero [11][12][13]. These anomalous light scattering effects have been exploited in multiple branches of physics ranging from boosting light collection efficiency in plants [14], to dynamic control of cryptographic nanoprints [15], to maximizing the sensitivity of circular dichroism spectroscopy of chiral molecules [16][17][18][19]. The physical picture behind most of the aforementioned works consists of maximizing the efficiency of the scattered light while fulfilling the first Kerker condition.…”

Chiral Dielectric Metasurfaces for Highly Integrated, Broadband Circularly Polarized Antenna

“…However, the radiation and AR performance are still low in all of these results, and additional strategies are required to design useful CP antennas. Following the reasoning of chiral dielectric metasurfaces for enhanced chiroptical effects [18], we considered slanted slots etched at the center of each cylinder, as schematized in the inset of Figure 4a. This mechanism not only improved AR but also the whole operating performance of the antenna, as it can be seen from Figure 4a,b.…”

“…Recent approaches for enhancement of AR bandwidth in metallic antennas have employed two pair slots, as explained in Reference [21]. Alternatively, dielectric resonators with high-permittivity are known to support electric and magnetic resonances of different orders [8,10], in analogy with cylindrical nanostructures [18]. The near-field overlapping between nearby cylinders resembles the electronic-bands from well-localized atomic orbitals in the tight-binding model [26,27] in electromagnetic platforms known as metasurfaces.…”

“…This may be used to simultaneously improve the handedness of an electromagnetic source while enhancing its electromagnetic field intensity, which can be reached through the proper engineering of suitable chiral structures [ 16 ]. In fact, chirality concepts have been used to control electromagnetic wave propagation in the microwave and optical domains [ 17 , 18 , 19 ], which serves as inspiration for CP antenna design.…”

“…In contrast to previous antenna designs using bulky metallic-based chiral metasurfaces [ 14 , 15 ], we exploit the pairing of electric and magnetic resonances of high-permittivity ( ) cylindrical resonators with slanted slots at the center. An analogous concept in nanophotonics yielded an enhanced broadband near- and far-field chiroptical activity [ 18 ]. To reach optimized radiation patterns with high gain and wide AR-BW, we used a arrangement of slotted cylinders.…”