We propose a wide-angle, polarization-independent and dual-band infrared perfect metamaterial absorber made of double L-shaped gold patches on a dielectric spacer and opaque gold ground layer. Numerical and experimental results demonstrate that the absorber has two near-unity absorption peaks, which are result from magnetic polariton modes generated at two different resonant wavelengths. In addition, the proposed structure also shows good absorption stability in a wide range of incident anglesθfor both TE and TM incidences at azimuthal angle φ = 0°. Moreover, we demonstrate that such structure has good absorption stability for a wide range of azimuthal angles due to the excitation of perpendicular magnetic polariton modes within the asymmetric double L-shaped structure. Such structure will assist in designing magnetic polaritons absorbing element for infrared spectroscopy and imaging.

Nanojet effects excited by surface plasmon polariton at the shadow-side surfaces of dielectric microdisks positioned on gold films are reported. The surface plasmon nanojet can propagate over several optical wavelengths while still maintaining a subwavelength full-width at half-maximum transverse. Due to the nature of surface plasmon wave, the electric field of the highly confined nanojet at metal-dielectric interface is enhanced by about 30 times. By varying thickness of the dielectric microdisk, the formation of surface plasmon polariton nanojet can be flexibly controlled. The surface plasmon polariton nanojet shows great promise for enhanced Raman scattering and integrated plasmonic circuits.

In this research paper, multiple trapped modes within a bi-periodic silicon particle array were studied numerically both through finite difference time domain method and finite element method. Anti-phased electric dipole, magnetic dipole, and magnetic quadrupole collective resonances in the two arrays result in three distinct trapped modes, which interact with the corresponding "bright modes" generating three sharp asymmetric Fano profiles in reflection. The lineshapes can be easily tailored by particle radius to achieve very narrow linewidth, while still remains 100% modulation depth. As a three-channel refractive sensor, the sensitivities for three working frequencies are 155 nm/RIU, 725 nm/RIU, and 190 nm/RIU.

In this research paper, a new type of Fano resonance originating from the far-field interference of lattice collective resonances of two sets of interlacing silver particle arrays with different radii is investigated numerically. The anti-phased collective resonance of the two arrays acts as "dark state", while the phased one serves as "bright state". The structure has the advantage to achieve both high modulation depth and sharp linewidth simultaneously, which is very attractive for plasmonic sensor, and the sensitivity and figure of merit can reach as high as 633 nm/RIU and 2000, respectively. Also, the structure has the merit of high Q factor up to 320.

We proposed a gradient dielectric-filled metallic grating to spatially localize wide-band terahertz waves at different locations for different frequencies. The dispersion relations for terahertz waves propagating along gratings with different filling-depths were developed under the first-order approximation based on the spoof surface plasmon theory. The structure can localize terahertz waves at the frequency regime from 0.7 to 1.3 THz, as the filling-depth H gradually increases from 0 to 50 µm. By filling with active media such as nematic liquid crystals, the trapping location can be effectively tuned, providing potential to realize controllable and compact integrated THz devices.