Enhancing LED spectral output with perylene dye-based remote phosphor.

LEDs offer a wide range of spectral output with high efficiencies. However, the efficiencies of solid-state LEDs with green and yellow wavelengths are rather low due to the lack of suitable direct bandgap materials. Here, we introduce and develop perylene-enhanced green LEDs that produce a higher wall-plug efficiency of 48% compared to 38% for a solid-state green LED.

Phase Matching via Plasmonic Modal Dispersion for Third Harmonic Generation.

The overall effectiveness of nonlinear optical processes along extended nonlinear media highly depends on the fulfillment of the phase-matching condition for pump and generated fields. This is traditionally accomplished by exploiting the birefringence of nonlinear crystals requiring long interaction lengths (cm-scale). For nonbirefringent media and integrated photonic devices, modal phase matching can compensate the index mismatch.

Optical Anisotropy in van der Waals materials: Impact on Direct Excitation of Plasmons and Photons by Quantum Tunneling.

Inelastic quantum mechanical tunneling of electrons across plasmonic tunnel junctions can lead to surface plasmon polariton (SPP) and photon emission. So far, the optical properties of such junctions have been controlled by changing the shape, or the type of the material, of the electrodes, primarily with the aim to improve SPP or photon emission efficiencies. Here we show that by tuning the tunneling barrier itself, the efficiency of the inelastic tunneling rates can be improved by a factor of 3.

CMOS-Compatible Electronic-Plasmonic Transducers Based on Plasmonic Tunnel Junctions and Schottky Diodes.

To develop methods to generate, manipulate, and detect plasmonic signals by electrical means with complementary metal-oxide-semiconductor (CMOS)-compatible materials is essential to realize on-chip electronic-plasmonic transduction. Here, electrically driven, CMOS-compatible electronic-plasmonic transducers with Al-AlO -Cu tunnel junctions as the excitation source of surface plasmon polaritons (SPPs) and Si-Cu Schottky diodes as the detector of SPPs, connected via plasmonic strip waveguides of Cu, are demonstrated. Remarkably, the electronic-plasmonic transducers exhibit overall transduction efficiency of 1.

Geometric control over surface plasmon polariton out-coupling pathways in metal-insulator-metal tunnel junctions.

Metal-insulator-metal tunnel junctions (MIM-TJs) can electrically excite surface plasmon polaritons (SPPs) well below the diffraction limit. When inelastically tunneling electrons traverse the tunnel barrier under applied external voltage, a highly confined cavity mode (MIM-SPP) is excited, which further out-couples from the MIM-TJ to photons and single-interface SPPs via multiple pathways. In this work we control the out-coupling pathways of the MIM-SPP mode by engineering the geometry of the MIM-TJ.

Low loss waveguiding and slow light modes in coupled subwavelength silicon Mie resonators.

Subwavelength light-guiding optical devices have gained great attention in the photonics community because they provide unique opportunities for miniaturization and functionality of the optical interconnect technology. On the other hand, high-refractive-index dielectric nanoparticles working at their fundamental Mie resonances have recently opened new venues to enhance and control light-matter interactions at the nanoscale while being free from Ohmic losses. Combining the best of both worlds, here we experimentally demonstrate low-loss slow light waveguiding in a chain of coupled silicon Mie resonators at telecommunication wavelengths.

Collective Mie Resonances for Directional On-Chip Nanolasers.

A highly efficient nanocavity formed by optically coupled nanostructures is achieved by optimization of the collective Mie resonances in a one-dimensional array of semiconductor nanoparticles. Analysis of quasi-normal multipole modes enables us to reveal the close relation between the collective Mie resonances and Van Hove singularities. On the basis of these concepts, we experimentally demonstrate a directional GaAs nanolaser at cryogenic temperatures with well-defined, in-plane emission, which, moreover, can be controlled by selective excitation.

Efficient Surface Plasmon Polariton Excitation and Control over Outcoupling Mechanisms in Metal-Insulator-Metal Tunneling Junctions.

Surface plasmon polaritons (SPPs) are viable candidates for integration into on-chip nano-circuitry that allow access to high data bandwidths and low energy consumption. Metal-insulator-metal tunneling junctions (MIM-TJs) have recently been shown to excite and detect SPPs electrically; however, experimentally measured efficiencies and outcoupling mechanisms are not fully understood. It is shown that the MIM-TJ cavity SPP mode (MIM-SPP) can outcouple via three pathways to i) photons via scattering of MIM-SPP at the MIM-TJ interfaces, ii) SPPs at the metal-dielectric interfaces (bound-SPPs) by mode coupling through the electrodes, and iii) photons and bound-SPP modes by mode coupling at the MIM-TJ edges.

Directional Excitation of Surface Plasmon Polaritons via Molecular Through-Bond Tunneling across Double-Barrier Tunnel Junctions.

Directional excitation of surface plasmon polaritons (SPPs) by electrical means is important for the integration of plasmonics with molecular electronics or steering signals toward other components. We report electrically driven SPP sources based on quantum mechanical tunneling across molecular double-barrier junctions, where the tunneling pathway is defined by the molecules' chemical structure as well as by their tilt angle with respect to the surface normal. Self-assembled monolayers of S(CH)BPh (BPh = biphenyl, = 1-7) on Au, where the alkyl chain and the BPh units define two distinct tunnel barriers in series, were used to demonstrate and control the geometrical effects.

Freestanding dielectric nanohole array metasurface for mid-infrared wavelength applications.

We designed and simulated freestanding dielectric optical metasurfaces based on arrays of etched nanoholes in a silicon membrane. We showed 2π phase control and high forward transmission at mid-infrared (mid-IR) wavelengths around 4.2 μm by tuning the dimensions of the holes.

Highly efficient tunable and localized on-chip electrical plasmon source using protruded metal-insulator-metal structure.

A compact and highly efficient tunable and localized source of propagating surface plasmon-polaritons is proposed based on a protruded metal-insulator-metal (pMIM) structure. The protrusion along a segment of the pMIM forms a nanometer gap and allows a low voltage bias to generate a localized tunneling current. The tunneling current excited plasmons can be fully coupled to the metal-insulator-metal (MIM) waveguiding segment of the pMIM without leakage and propagate a long distance as the gap in the MIM waveguiding segment is much larger than the gap in the protruded segment of the pMIM.

Second-Harmonic Generation from Sub-5 nm Gaps by Directed Self-Assembly of Nanoparticles onto Template-Stripped Gold Substrates.

Strong field enhancement and confinement in plasmonic nanostructures provide suitable conditions for nonlinear optics in ultracompact dimensions. Despite these enhancements, second-harmonic generation (SHG) is still inefficient due to the centrosymmetric crystal structure of the bulk metals used, e.g.

Electro-optical graphene plasmonic logic gates.

The versatile control of graphene's plasmonic modes via an external gate-voltage inspires us to design efficient electro-optical graphene plasmonic logic gates at the midinfrared wavelengths. We show that these devices are superior to the conventional optical logic gates because the former possess cut-off states and interferometric effects. Moreover, the designed six basic logic gates (i.

Submicrometer radius and highly confined plasmonic ring resonator filters based on hybrid metal-oxide-semiconductor waveguide.

We numerically report the submicrometer radius (0.5 μm) and high confinement (mode area ~λ(2)/1200) plasmonic ring resonators for both all-pass and add-drop filters based on the hybrid metal-oxide-semiconductor (Ag-SiO(2)-Si) waveguide platform. The best tradeoff between the propagation length and the confinement of this hybrid plasmonic waveguide platform is also discussed and compared to the dielectric-loaded plasmonic waveguide counterpart.

Volume integral equation analysis of surface plasmon resonance of nanoparticles.

The interactions between electromagnetic field and arbitrarily shaped metallic nanoparticles are numerically investigated. The scattering and near field intensity of nanoparticles are characterized by using volume integral equation which is formulated by considering the total electric field, i.e.

Analysis of sub-wavelength light propagation through long double-chain nanowires with funnel feeding.

The surface integral equation (SIE) method is utilized to characterize plasmonic waveguide made of two parallel chains of silver nanowires with radius of 25nm fed by a V-shaped funnel at a working wavelength of 600nm. The efficiency of energy transport along the waveguide due to surface plasmonic coupling is investigated for different dimensions and shapes. The opening angle of the V-shaped funnel region for optimum light capturing is included in the investigation as well.