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Recent development in nanofabrication technology has enabled the fabrication of plasmonic nanoapertures that can provide strong field concentrations beyond the diffraction limit. Further utilization of plasmonic nanoaperture requires the broadband tuning of the operating wavelength and precise control of aperture geometry. Here, we present a novel plasmonic coaxial aperture that can support resonant extraordinary optical transmission (EOT) with a peak transmittance of ~10% and a wide tuning range over a few hundred nanometers. Because of the shadow deposition process, we could precisely control the gap size of the coaxial aperture down to the sub–10-nm scale. The plasmonic resonance of the SiNx/Au disk at the center of the coaxial aperture efficiently funnels the incident light into the sub–10-nm gap and allows strong electric field confinement for efficient second harmonic generation (SHG), as well as EOT. In addition to the experiment, we theoretically investigated the modal properties of the plasmonic coaxial aperture depending on the structural parameters and correlation between EOT and SHG through finite-difference time-domain simulations. We believe that our plasmonic coaxial apertures, which are readily fabricated by the nanoimprinting process, can be a versatile, practical platform for enhanced light–matter interaction and its nonlinear optical applications.

The non-equilibrium state between magnons and phonons is the key to understand the spin-caloric phenomena. We developed a unique optical reflectometry technique to spatially resolve Kerr angle ( θ K ) and optical reflectance (R) in a magnetic insulator—thulium iron garnet (TmIG). The TmIG was subjected to a thermal gradient to estimate populations of thermally excited magnons and phonons through the variation of θ K and R. The results showed that the spatial gradient of θ K is different from that of R , indicating the non-equilibrium state between magnons and phonons. Particularly, the characteristic decay length of θ K was significantly influenced by the heating power and the magnetic field, suggesting non-linear magnon scattering in a high magnon density regime. Our work not only provides a scheme to investigate the spatial profiles of magnons and phonons but also reveals the magnon–phonon non-equilibrium in TmIG. Hence, this report will stimulate further studies based on magnon–phonon non-equilibrium such as a transverse spin Seebeck effect and Bose–Einstein condensation. [ABSTRACT FROM AUTHOR]

Holographic stereography providing binocular depth cues is one of the most promising technologies for 3D displays. However, conventional holographic stereograms based on micrometer‐scale pixels suffer from multiple diffraction orders and narrow viewing angles. Optical metasurfaces with sub‐wavelength‐scale features have recently been leading amongst the state‐of‐the‐art technologies in 3D holograms but employing only monocular depth cues. Here, a novel method is presented based on optical metasurfaces for obtaining a binocular holographic stereopsis. The demonstrated optical metasurface is an ensemble of several hologram pieces, which produce the different 2D projections of the target 3D structure depending on the observation direction, and displays the holographic stereogram of 25 × 25 × 25 µm3 over a wide viewing angle of more than ±30°. A Gerchberg–Saxton algorithm modified with a spatial Fourier filter calculates the phase and amplitude distribution of meta‐atoms. The results will open avenues to advanced eyeglasses‐free 3D displays that can provide rich and well‐defined depth cues. [ABSTRACT FROM AUTHOR]

Magneto-optic Kerr effect (MOKE) enhancement is studied for Yttrium Iron Garnet (YIG) nanoparticle. The MOKE is quantified by the ratio of the polarization components of reflected wave, namely between the perpendicular component to the parallel component with respect to the polarization of the incident wave. Thus, the enhancement of MOKE can be obtained by increasing the perpendicular component or reducing the parallel component of the reflected wave polarization. An FDTD calculation is performed to obtain the scattered field. Projecting the resulting scattered field to the vector spherical harmonic basis, we show through multipole moments analysis that the suppression of backscattering non-MO field and the raise of the backscattered MO field can be achieved by subtle superposition of some optical modes. For the specific YIG particle system and the wavelength range chosen, the result shows that enhancement of MOKE up to 7.5 mrad can be achieved. [ABSTRACT FROM AUTHOR]

Abstract: Structural colors generated by optical micro‐ or nanostructures have attracted much attention for replacing pigment colors due to their tunability and semipermanency. The advantages of structural colors are now ready to be extended to the spectral range outside that of visible wavelengths. Here, bright structural colors are demonstrated in the near‐ultraviolet (near‐UV) wavelength range based on the plasmonic resonance of an aluminum nanodisk array. Collective plasmonic oscillation of the aluminum nanodisks selectively reflects the near‐UV light with a high reflectance and narrow linewidth. The color of the reflected light is tuned over the full near‐UV range, depending on the structural parameters of the nanodisk array. In particular, aluminum nanodisk arrays can be used as structural color pixels that demonstrate printing of near‐UV images with a high resolution of ≈10 000 pixels per inch. The demonstrated near‐UV structural colors show significant progress toward UV filtering and imaging, anticounterfeit, color multiplexing, and photocatalysis. [ABSTRACT FROM AUTHOR]

Telomerase has attracted much attention as a universal cancer biomarker because telomerase is overexpressed in more than 85% of human cancer cells while suppressed in normal somatic cells. Since a strong association exists between telomerase activity and human cancers, the development of effective telomerase activity assay is critically important. Here, a nanogap-rich Au nanowire (NW) surface-enhanced Raman scattering (SERS) sensor is reported for detection of telomerase activity in various cancer cells and tissues. The nanogap-rich Au NWs are constructed by deposition of nanoparticles on single-crystalline Au NWs and provided highly reproducible SERS spectra. The telomeric substrate (TS) primer-attached nanogap-rich Au NWs can detect telomerase activity through SERS measurement after the elongation of TS primers, folding into G-quadruplex structures, and intercalation of methylene blue. This sensor enables us to detect telomerase activity from various cancer cell lines with a detection limit of 0.2 cancer cells mL−1. Importantly, the nanogap-rich Au NW sensor can diagnose gastric and breast cancer tissues accurately. The nanogap-rich Au NW sensors show strong SERS signals only in the presence of tumor tissues excised from 16 tumor-bearing mice, while negligible signals in the presence of heated tumor tissues or normal tissues. It is anticipated that nanogap-rich Au NW SERS sensors can be used for a universal cancer diagnosis and further biomedical applications including a diverse biomarker sensing. [ABSTRACT FROM AUTHOR]

This paper examines the relationships between environmental uncertainty, franchise core competency, competitive advantage, and financial performance within the context of food-service franchise companies that build and maintain harmony between external characteristics and internal resources and competency. A survey of 156 food-service franchise firms provides the basis for this empirical investigation. Findings show that both environmental uncertainty and franchise core competency can lead to firm success – but in very different ways. Franchise core competency enhances firm performance by providing differentiation advantage, whereas environmental uncertainty improves performance through franchise core competency. This paper discusses the implications of these findings for researchers and managers. [ABSTRACT FROM PUBLISHER]

The miniaturization of electronic and photonic device technologies has facilitated information processing and transport at ever-increasing speeds and decreasing power levels. Nanometallics or 'plasmonics' has empowered us to break the diffraction limit and open the door to the development of truly nanoscale optical circuits. A logical next step in this development is the realization of compact optical sources capable of electrically driving such nanocircuits. Nanometallic lasers are a possible candidate, but the realization of power-efficient, electrically pumped nanolasers at room temperature is extremely challenging. Here, we explore a plasmonic light-emitting diode as a possible alternative option. We demonstrate that an electrically driven, nano light-emitting diode is capable of directing light emission into a single-mode plasmon waveguide with a cross-sectional area of 0.016λ2 by exploiting the Purcell effect. With this source, electrically driven subwavelength optical nanocircuits for routing, splitting, free-space coupling and directional coupling are realized for the first time. [ABSTRACT FROM AUTHOR]