Lattice Zenneck Modes on Subwavelength Antennas

Abstract

Optical resonances in isolated nanoparticles made out of commonly occurring materials with high optical losses, such as transition metal dichalcogenides, germanium, carbide, and others, are weak and not sufficient for field enhancement and competing with plasmonic resonances in noble metal nanoparticles. This work presents a novel approach to achieve strong resonances in the arrays of such nanoparticles with large optical losses and points to their potential for efficient light control in ultra‐thin optical elements, sensing, and photovoltaic applications. Materials with large imaginary part of permittivity (LIPP) are studied and nanostructures of these materials are shown to support not only surfaces modes, known as Zenneck waves, but also modes localized on the subwavelength particle. This approach opens up the possibility of exciting strong localized nanoparticle resonances without involving plasmonic or high‐refractive‐index materials. Arranging LIPP particles in a periodic array plays a crucial role allowing for collective array resonances, which are shown to be much stronger in particle array than in single particle. The collective lattice resonances can be excited at the wavelength defined mainly by the array period and thus easily tuned in a broad spectral range not being limited by particle permittivity, size, or shape.

Multipole Mie Resonances in MXene-Antenna Arrays

“…The overall behavior of an array is primarily determined by the collective properties of its constituent elements. This implies that the characteristics of individual antennas have a lesser influence on the array’s behavior. , Processing Ti 3 C 2 T x materials is very challenging and requires developing a number of steps, and instead, we perform proof-of-concept experimental measurements of titanium array on the silica substrate in the near-infrared range. Figure shows the experimental demonstration of the lattice resonance in the array of titanium antennas (see the Methods section).…”

“…Analytical models for periodic arrays of spherical antennas have been developed in previous studies (refs and ). These models use coupled dipole–quadrupole equations to calculate the optical response of an infinite lattice consisting of multipoles.…”

Optical Processes behind Plasmonic Applications

“…A novel method for achieving strong resonances in nanoparticle arrays with high optical losses has been proposed in a recent study [ 85 ], which holds the potential for efficient light manipulation in ultra-thin optical elements, sensing, and photovoltaic applications. Strongly localized nanoparticle resonances can be excited in materials with a large imaginary part of permittivity [ 86 , 87 ].…”

“…Transition metal dichalcogenides, including tungsten disulfide WS , possess large permittivity and support well-defined Mie resonances [ 88 , 89 ]. A periodic array of WS nanoantennas can control different multipole resonances via the lattice period [ 85 ], making it a potential tool for future nanophotonic devices.…”

Lattice Resonances in Transdimensional WS2 Nanoantenna Arrays

“…Layered material anisotropy results in different in-plane and out-of-plane permittivity components, and the excitons in visible range result in a large imaginary part of the permittivity along with the increased real part. A large imaginary part not only causes non-radiative losses but also facilities excitation of Zenneck modes and light confinement within the guiding nanolayer [13] or nanoparticles [14]. In the near-infrared range, the losses in TMDCs are near zero, and the nanoparticle can support Mie resonances with high quality factor [15].…”