Structural colors traditionally refer to colors arising from the interaction of light with structures with periodicities on the order of the wavelength. Recently, the definition has been broadened ...

Nanophotonic Structural Colors

Broadband solar energy absorber based on monolayer molybdenum disulfide using tungsten elliptical arrays

By means of critical coupling and impedance matching theory, we have numerically simulated the perfect absorption of monolayer graphene. Through the critical coupling effect and impedance matching, we studied a perfect single-band absorption of the monolayer graphene and obtained high quality factor (Q-factor = 664.2) absorption spectrum which has an absorbance close to 100% in the near infrared region. The position of the absorption spectrum can be adjusted by changing the ratio between the radii of the elliptic cylinder air hole and the structural period. The sensitivity of the absorber can be achieved S = 342.7 nm/RIU (RIU is the per refractive index unit) and FOM = 199.2 (FOM is the figure of merit), which has great potential for development on biosensors. We believe that our research will have good application prospects in graphene photonic devices and optoelectronic devices.

https://www.mdpi.com/2079-4991/10/1/95/pdf

High Quality Factor, High Sensitivity Metamaterial Graphene-Perfect Absorber Based on Critical Coupling Theory and Impedance Matching.

Gold nanorods (NRs), pseudo-one-dimensional rod-shaped nanoparticles (NPs), have become one of the burgeoning materials in the recent years due to their anisotropic shape and adjustable plasmonic properties. With the continuous improvement in synthetic methods, a variety of materials have been attached around Au NRs to achieve unexpected or improved plasmonic properties and explore state-of-the-art technologies. In this review, we comprehensively summarize the latest progress on Au NRs, the most versatile anisotropic plasmonic NPs. We present a representative overview of the advances in the synthetic strategies and outline an extensive catalogue of Au-NR-based heterostructures with tailored architectures and special functionalities. The bottom-up assembly of Au NRs into preprogrammed metastructures is then discussed, as well as the design principles. We also provide a systematic elucidation of the different plasmonic properties associated with the Au-NR-based structures, followed by a discussion of the promising applications of Au NRs in various fields. We finally discuss the future research directions and challenges of Au NRs.

Gold Nanorods: The Most Versatile Plasmonic Nanoparticles

Received 17 January 2007; accepted 4 April 2007The role of surface plasmon in second harmonic generation from arrays of gold nanorod particlesexcited by femtosecond laser pulses is investigated as a function of incident light polarization andirradiation wavelength. In addition to photoluminescence, a peak of second harmonic is observedand is found to depend on the polarization and wavelength of the fundamental frequency laser beam.In particular, the authors found similarities between extinction spectra of the nanoparticles andspectra of emmitted second harmonic. This behavior can be explained by resonant excitation oflocalized surface plasmon resonances. ©

PROOF COPY 108717APL Role of surface plasmon in second harmonic generation from gold nanorods

We present an ultra-broadband perfect absorber composed of metal-insulator composite multilayer (MICM) stacks by placing the insulator-metal-insulator (IMI) grating on the metal-insulator-metal (MIM) film stacks. The absorber shows over 90% absorption spanning between 570 nm and 3539 nm, with an average absorption of 97% under normal incidence. The ultra-broadband perfect absorption characteristics are achieved by the synergy of guided mode resonances (GMRs), localized surface plasmons (LSPs), propagating surface plasmons (PSPs), and cavity modes. The polarization insensitivity is demonstrated by analyzing the absorption performance over arbitrary polarization angles. The ultra-broadband absorption remains more than 80% over a wide incident angle up to 50°, for both transverse electric (TE) and transverse magnetic (TM) modes. The ultra-broadband perfect absorber has tremendous potential for various applications, such as solar thermal energy harvesting, thermoelectrics, and imaging.

Ultra-broadband perfect absorber utilizing refractory materials in metal-insulator composite multilayer stacks

We propose a high-quality multispectral plasmonic sensor by coating a dielectric grating on the semiconductor-metal-semiconductor stacks. Ultra-narrow plasmonic resonances with the minimum bandwidth of 8 nm are insensitive to the polarization of incident light. The ultra-narrow multi-band phenomenon can be ascribed to the synergy of guided mode resonances, cavity modes and surface plasmon polaritons. The sensor displays superior refractive index sensitivity (404.295 nm/RIU) and figure of merit (50.3) and can also be used to detect the protein layer in sub-nanometer thickness. These offer new perspectives for achieving ultra-compact efficient sensors and filters.

https://iopscience.iop.org/article/10.7567/1882-0786/ab24af/pdf

Grating-assisted ultra-narrow multispectral plasmonic resonances for sensing application

Polarization and angle insensitive ultra-broadband mid-infrared perfect absorber

Split graphene nano-disks with tunable, multi-band, and high-Q plasmon modes

We propose a new ultra-broadband metamaterial absorber based on a titanium-silica-titanium sandwich structure, which is composed of a periodic array of titanium-silica elliptical nanodisks and a titanium bottom film. The absorption bandwidth reaches 1376 nm in the wavelength range from visible to near-infrared region with the spectral absorptivity > 90%. Moreover, the spectrally averaged absorption is up to 94.6%, indicating the achievement of ultra-broadband near-perfect absorption. In addition, the near-perfect absorption is polarization-independent and incident-angle insensitive. The ultra-broadband absorption is mainly results from the strong plasmonic near-field coupling by the adjacent metal parts and the intrinsic material absorption in the wide wavelength range by the refractory metal. The proposed ultra-broadband metamaterial absorber could hold broad application prospects in solar photovoltaic generation, infrared detection, and hot-electron devices.

https://iopscience.iop.org/article/10.1088/1361-6463/ab5d41/pdf

Biao Wu

Papers

Ultra-broadband perfect absorber utilizing refractory materials in metal-insulator composite multilayer stacks

Grating-assisted ultra-narrow multispectral plasmonic resonances for sensing application

Polarization and angle insensitive ultra-broadband mid-infrared perfect absorber

Split graphene nano-disks with tunable, multi-band, and high-Q plasmon modes

An ultra-broadband, polarization and angle-insensitive metamaterial light absorber