The development of a thresholdless laser operating above room temperature (RT) is key for the future replacement electronics with photonic integrated circuits, enabling an increase several orders magnitude in computing speeds. Recently, lasing characteristics at low (4 K) have been demonstrated. However, practical applications, RT emission becomes necessary. Here we report experimental evidence that compatible based on InAsSb quantum dots embedded photonic-crystal microcavity exhibits...

The optomechanical coupling that emerges in an optical cavity which one of the mirrors is a mechanical resonator has allowed sub-Kelvin cooling with prospect observing quantum phenomena and self-sustained oscillators very high spectral purity. Both applications clearly benefit from use smallest possible resonator. Unfortunately, largely decays when size system below light wavelength. Here, we propose to exploit resonances associated confinement subwavelength structures circumvent this...

Mechanical transducers based on nanowires promise revolutionary advances in biological sensing and force microscopy/spectroscopy. A crucial step is the development of simple non-invasive techniques able to detect displacements with subpicometer sensitivity per unit bandwidth. Here, we design suspended tapered silicon supporting a range optical resonances that confine efficiently scatter light visible range. Then, develop an method for coupling evanescent field regular interference pattern...

The electronic states of novel semiconductor quantum rings (QR's) under applied lateral electric fields are theoretically investigated for different values the ratio ${r}_{2}{/r}_{1},$ where ${r}_{2}$ ${(r}_{1})$ is outer (inner) radius ring. eigenstates and eigenvalues Hamiltonian obtained from a direct matrix diagonalization scheme. Numerical calculations performed hard-wall confinement potential as function field ${r}_{2}{/r}_{1}.$ An anomalous behavior in energy vs. electric-field fan...

The origin of the modified optical properties InAs/GaAs quantum dots (QD) capped with a thin GaAs1−xSbx layer is analyzed in terms band structure. To do so, size, shape, and composition QDs capping are determined through cross-sectional scanning tunnelling microscopy used as input parameters an 8 × k·p model. As Sb content increased, there two competing effects determining carrier confinement oscillator strength: increased QD height reduced strain on one side QD-capping valence offset other....

Abstract Bound states in the continuum (BICs) emerge throughout physics as leaky/resonant modes that remain, however, highly localized. They have attracted much attention photonics, and especially metasurfaces. One of their most outstanding features is divergent Q-factors, indeed arbitrarily large upon approaching BIC condition (quasi-BICs). Here, we investigate how to tune quasi-BICs magneto-optic (MO) all-dielectric The impact applied magnetic field parameter space revealed for a...

The photoluminescence efficiency of GaAsSb-capped InAs/GaAs type II quantum dots (QDs) can be greatly enhanced by rapid thermal annealing while preserving long radiative lifetimes which are ∼20 times larger than in standard GaAs-capped QDs. Despite the reduced electron-hole wavefunction overlap, type-II samples more efficient type-I counterparts terms luminescence, showing a great potential for device applications. Strain-driven In-Ga intermixing during is found to modify QD shape and...

Multi-junction solar cells made by assembling semiconductor materials with different bandgap energies have hold the record conversion efficiencies for many years and are currently approaching 50%. Theoretical efficiency limits make use of optimum designs right lattice constant-bandgap energy combination, which requires a 1.0-1.15 eV material lattice-matched to GaAs/Ge. Nevertheless, lack suitable is hindering achievement predicted efficiencies, since only candidates were up now complex...

Room-temperature (RT), on-chip deterministic generation of indistinguishable photons coupled to photonic integrated circuits is key for quantum applications. Nevertheless, high indistinguishability (I) at RT difficult obtain due the intrinsic dephasing most single-photon sources (SPS). Here, we present a numerical demonstration design and optimization hybrid slot-Bragg nanophotonic cavity that achieves theoretical near-unity I coupling efficiency (β) variety emitters. Our simulations predict...

III-V solar cells dominate the high efficiency charts, but with significantly higher cost than other cells. Ultrathin can exhibit lower production costs and immunity to short carrier diffusion lengths caused by radiation damage, dislocations, or native defects. Nevertheless, solving incomplete optical absorption of sub-micron layers presents a challenge for light-trapping structures. Simple photonic crystals have diffractive efficiencies, which are excellent narrow-band applications. Random...

We study optical back-action effects associated with confined electromagnetic modes in silicon nanowire resonators interacting a laser beam used for interferometric read-out of the vibrations. Our analysis describes resonance frequency shift produced nanowires by two different mechanisms: temperature dependence nanowire's Young's modulus and effect radiation pressure. find regimes which each dominates depending on morphology dimensions, resulting either positive or negative shifts. results...

Soft lithography allows for the simple and low-cost fabrication of nanopatterns with different shapes sizes over large areas. However, resolution aspect ratio nanostructures fabricated by soft are limited depth physical properties stamp. In this work, silicon nanobelts were achieved combining nanolithography patterning optimized reactive ion etching (RIE) in silicon. Using polymethylmethacrylate (PMMA) nanopatterned layers thicknesses ranging between 14 50 nm, we obtained areas square...

Abstract The moth-eye structure has been proposed several times as an antireflective coating to replace the standard optical thin films. Here, we experimentally demonstrate feasibility of a dielectric for high-index substrates, like GaAs. fabricated photonic crystal Si 3 N 4 cones in square lattice, sitting on top TiO 2 index matching layer. This attains 1.4% reflectance power losses operation spectral range GaAs solar cells (440–870 nm), 12.5% relative reduction reflection comparison with...

Medium energy ion scattering (MEIS) has been used to measure at the scale of monolayer deformation profile self-organized GaN quantum dots grown on AlN by molecular-beam epitaxy. The effect capping a thin layer also studied. It is shown that are partially relaxed in every situation. Capping them with little basal plane, as expected, but strongly modifies strain upper part dots. experimental results compared theoretical calculations, allowing one conclude experience nonbiaxial strain, which...

The optical absorption in a homogeneous and non-dispersive slab is governed by the well-known Fabry-Perot resonances. We have found that below lowest order resonance, there another maximum due to zero frequency mode whose peak given not real part of complex resonance frequency, as it case for all other resonances, but imaginary part. This result interest, among applications, ultra thin solar cells, tuning with irradiance results an increased efficiency.

Broadband solar cell antireflection coatings made of nano-cones are studied in square lattices ZnS, TiO(2) and Si(3)N(4). In the best case, spectrally integrated transmittance (accounting for both reflection dielectric absorption losses) direct radiation is 99 %, which represents a four-fold decrease transmission losses comparison to standard antireflective coating bilayer. The dependence as function nanostructure dimensions studied, showing wide maximum, thus leading high tolerance...

A series of photonic crystal structures are optimized for a photon enhanced thermionic emitter. With realistic parameter values to describe p-type GaAs device we find an efficiency above 10%. The light-trapping increases the performance by 2% over optimal bilayer anti-reflective coating. We very close case Lambertian absorber, but below its maximum performance. To prevent 10% vacuum gap must be dimensioned according concentration factor solar irradiance.

External control over the electron and hole wavefunctions geometry topology is investigated in a p-i-n diode embedding dot-in-a-well InAs/GaAsSb quantum structure with type II band alignment. We find highly tunable exciton dipole moments largely decoupled recombination ionization dynamics. also predicted bias regime where wavefunction changes continuously from dot-like to ring-like as function of external bias. All these properties have great potential advanced electro-optical applications...

Self-assembled $\mathrm{Ga}\mathrm{N}∕\mathrm{Al}\mathrm{N}$ quantum dots have been investigated by means of Raman scattering. A resonant enhancement the peaks has observed when excitation is tuned above GaN band-gap energy. The polar mode nature, either quasiconfined or interfacial, assigned after comparing with optical modes spheroidal calculated within framework anisotropic dielectric continuum model. built-in strain induced a substantial blueshift nonpolar ${E}_{2H}$ frequency....

The Purcell effect dependence on the excitation power is studied in photonic crystal microcavity lasers embedding InAs/InP quantum wires. In case of non-lasing modes, has low optical pumping, attributable to an exciton dynamics combining free and localized excitons. lasing influence stimulated emission makes ambiguous determination factor. We have found that this ambiguity can be avoided by measuring decay time power. These results provide insights factor lasers.

The growth of compound semiconductors on silicon has been widely sought after for decades, but reliable methods defect-free combination these materials have remained elusive. Recently, interconnected GaAs nanoscale membranes used as templates the scalable integration nanowire networks III-V substrates. Here, we demonstrate how can be seamlessly integrated by controlling density nuclei in initial stages growth. We also correlate absence or presence defects with existence a single multiple...

We present experimental evidence of Sb incorporation inside InAs/GaA(001) quantum dots exposed to an antimony flux immediately before capping with GaAs. The composition profile the nanostructures as measured by cross-sectional scanning tunneling and electron transmission microscopies show two differentiated regions within dots, rich alloy at tip dots. Atomic force microscopy micrographs increased quantum-dot height exposure. evolution reflection high-energy electron-diffraction pattern...

Abstract Electrical contacts on the top surface of solar cells and light emitting diodes cause shadow losses. The phenomenon extraordinary optical transmission through arrays subwavelength holes suggests possibility engineering such to reduce using plasmonics, but resonance effects occur only at specific wavelengths. Here we describe instead a broadband effect enhanced metallic wires, due fact that, in absence resonances, metal wires asymptotically tend invisibility small size limit...

The electronic states of a semiconductor quantum ring (QR) under an applied lateral electric field are theoretically investigated and compared with those disk the same size. eigenstates eigenvalues Hamiltonian obtained from direct matrix diagonalization scheme. Numerical calculations performed for hard-wall confinement potential as function ratio r2/r1, where r2 (r1) is outer (inner) radius ring. effects decreasing symmetry mixing on energy levels wave functions due to also studied. optical...