Quantitative analysis of a III-V tapered horn-shaped metal-clad nano-cavity as an on-chip light source

A horn-shaped metal-clad InGaAsP nano-cavity with sloped sidewalls is proposed as a platform for nanoscale light sources. The nano-cavity’s physical dimensions are 350 × 350 × 350 nm^3, and its mode volume is 0.5 (λ_0/n)^3. In our numerical simulations and quantitative analysis, we have shown that the sloped sidewalls reduce metallic absorption and improve resonant mode confinement; and adjusting their slope from 0 to 16° increased the Q factor from 150 to 900 and laser modulation 3dB bandwidth from 4.3 to 36 GHz. The lasing threshold current was expected to be 35 μA at 16°. In a simulated feasibility study, we demonstrate 60 Gbps modulated laser signal (5 fJ/bit), producing 20 μW output power at the 1.5 μm wavelength with injection current 100 μA, as an implementation of horn-shaped nano-cavity platform to the low power and ultra-fast on-chip nano-laser

Top-down, decoupled control of constitutive parameters in electromagnetic metamaterials with dielectric resonators of internal anisotropy

A meta-atom platform providing decoupled tuning for the constitutive wave parameters remains as a challenging problem, since the proposition of Pendry. Here we propose an electromagnetic meta-atom design of internal anisotropy (ε_r ≠ ε_θ), as a pathway for decoupling of the effective- permittivity ε_(eff) and permeability μ_(eff). Deriving effective parameters for anisotropic meta-atom from the first principles, and then subsequent inverse-solving the obtained decoupled solution for a target set of ε_(eff) and μ_(eff), we also achieve an analytic, top-down determination for the internal structure of a meta-atom. To realize the anisotropy from isotropic materials, a particle of spatial permittivity modulation in r or θ direction is proposed. As an application example, a matched zero index dielectric meta-atom is demonstrated, to enable the super-funneling of a 50λ-wide flux through a sub-λ slit; unharnessing the flux collection limit dictated by the λ-zone

Acoustic omni meta-atom for decoupled access to all octants of a wave parameter space

The common behaviour of a wave is determined by wave parameters of its medium, which are generally associated with the characteristic oscillations of its corresponding elementary particles. In the context of metamaterials, the decoupled excitation of these fundamental oscillations would provide an ideal platform for top–down and reconfigurable access to the entire constitutive parameter space; however, this has remained as a conceivable problem that must be accomplished, after being pointed out by Pendry. Here by focusing on acoustic metamaterials, we achieve the decoupling of density ρ, modulus B^(−1) and bianisotropy ξ, by separating the paths of particle momentum to conform to the characteristic oscillations of each macroscopic wave parameter. Independent access to all octants of wave parameter space (ρ, B^(−1), ξ)=(+/−,+/−,+/−) is thus realized using a single platform that we call an omni meta-atom; as a building block that achieves top–down access to the target properties of metamaterials

Extraordinary Magnetic Field Enhancement with Metallic Nanowire: Role of Surface Impedance in Babinet's Principle for Sub-Skin-Depth Regime

We propose and analyze the "complementary" structure of a metallic nanogap, namely, the metallic nanowire for magnetic field enhancement. A huge enhancement of the field up to a factor of 300 was achieved. Introducing the surface impedance concept, we also develop and numerically confirm a new analytic theory which successfully predicts the field enhancement factors for metal nanostructures. Compared to the predictions of the classical Babinet principle applied to a nanogap, an order of magnitude difference in the field enhancement factor was observed for the sub-skin-depth regime nanowire

Glucose measurement using Surface Enhanced Raman Scattering

Surface Enhanced Raman Scattering (SERS) has a great potential to serve as a monitoring technology for biomolecules, but sensing biomolecules for practical purposes have remained challenging for two reasons. One of the challenges is securing SERS substrates with uniform spatial enhancement that is crucial for quantitative measurements, and the other is finding proper linker molecules that will promote the surface enhancement. To address these challenges, we have been developing a new approach of using highly sensitive surface enhanced Raman scattering (SERS) platform for glucose sensing. In the presentation, I will discuss the fabrication of high performance 3D SERS substrate based on straightforward, two successive wet chemical processes, with experimentally proven strong enhancement and excellent spatial uniformity as well as the use of new linker molecules for making glucose-specific SERS substrates and their use in performing quantitative glucose measurements. Glucose sensing results from different development stages will be discussed

Glucose measurement using Surface Enhanced Raman Scattering

Surface Enhanced Raman Scattering (SERS) has a great potential to serve as a monitoring technology for biomolecules, but sensing biomolecules for practical purposes have remained challenging for two reasons. One of the challenges is securing SERS substrates with uniform spatial enhancement that is crucial for quantitative measurements, and the other is finding proper linker molecules that will promote the surface enhancement. To address these challenges, we have been developing a new approach of using highly sensitive surface enhanced Raman scattering (SERS) platform for glucose sensing. In the presentation, I will discuss the fabrication of high performance 3D SERS substrate based on straightforward, two successive wet chemical processes, with experimentally proven strong enhancement and excellent spatial uniformity as well as the use of new linker molecules for making glucose-specific SERS substrates and their use in performing quantitative glucose measurements. Glucose sensing results from different development stages will be discussed

Optical magnetic field mapping using a subwavelength aperture

Local distribution of the optical magnetic field is a critical parameter in developing materials with artificially engineered optical properties. Optical magnetic field characterization in nano-scale remains a challenge, because of the weak matter-optical magnetic field interactions. Here, we demonstrate an experimental visualization of the optical magnetic field profiles by raster scanning circular apertures in metal film or in a conical probe. Optical magnetic fields of surface plasmon polaritons and radially polarized beam are visualized by measuring the transmission through metallic apertures, in excellent agreements with theoretical predictions. Our results show that Bethe-Bouwkamp aperture can be used in visualizing optical magnetic field profiles

Giant nonlinear response of terahertz nanoresonators on VO2 thin film

We report on an order of magnitude enhanced nonlinear response of vanadium dioxide thin film patterned with nanoresonators - nano slot antennas fabricated on the gold film. Transmission of terahertz radiation, little affected by an optical pumping for the case of bulk thin film, can now be completely switched-off: Delta T/T approximate to-0.9999 by the same optical pumping power. This unprecedentedly large optical pump-terahertz probe nonlinearity originates from the insulator-to-metal phase transition drastically reducing the antenna cross sections of the nanoresonators. Our scheme enables nanoscale-thin film technology to be used for all-optical switching of long wavelength light