Kerker Conditions upon Lossless, Absorption, and Optical Gain Regimes

Abstract

The directionality and polarization of light show peculiar properties when the scattering by a dielectric sphere can be described exclusively by electric and magnetic dipolar modes. Particularly, when these modes oscillate in phase with equal amplitude, at the so-called first Kerker condition, the zero optical backscattering condition emerges for nondissipating spheres. However, the role of absorption and optical gain in the first Kerker condition remains unexplored. In this work, we demonstrate that either absorption or optical gain precludes the first Kerker condition and, hence, the absence of backscattered radiation light, regardless of the particle's size, incident wavelength, and incoming polarization. Finally, we derive the necessary prerequisites of the second Kerker condition of the zero forward light scattering, finding that optical gain is a compulsory requirement.

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

“…1(b). Moreover, it is worth noticing that, for lossy spheres, the EM helicity cannot be preserved [23]. This physical picture remains valid for dissipating pure-multipolar regions such as dipolar regimes in the visible spectral range, e.g., a dielectric Ge nanosphere [23] or a Si nanosphere [29].…”

“…For each multipole order l, and according to Eqs. (2) and 3, this nonmagnetic generalized duality condition requires either S l (mx) = 0 or S l (mx) = 0 [22,23]. Generally, these solutions are embedded in…”

Human Body Specific Absorption Rate Reduction Employing a Compact Magneto-Dielectric AMC Structure for 5G Massive-MIMO Applications

“…By definition, an artificial magnetic conductor (AMC) is a structure, which shows a close-to-zero reflection coefficient phase, when it is subjected to the normal TEM plane wave illumination [9]. In their first appearance, AMCs were introduced as the periodic patches shorted to the ground planes via metallic pins [14]. However, they can also be implemented by loading a grounded dielectric substrate with different FSS-type periodic metallization [13].…”

“…Among all these approaches, Artificial Magnetic Conductor (AMC) can be an alternative for PEC to achieve our purposes, as it can act as a perfect magnetic conductor (PMC) at particular frequency bands. The AMC surface presents high impedance characteristics in some frequencies and changes the antenna's radiation pattern while maintaining antenna performances such as radiation efficiency and gain even when the antenna is too close to it [14]. In the aforementioned area, several research works have been proposed on AMC as a ground plane of the antenna to reduce RF exposure of mobile phones.…”

“…In the aforementioned area, several research works have been proposed on AMC as a ground plane of the antenna to reduce RF exposure of mobile phones. However, the size of the designed antenna is relatively significant [12][13][14][15].…”