Quantum dots (QDs) show great promise for use in nanotechnology, owing to their high quantum efficiency, color tenability, narrow emission, and luminescence efficiency. As a new generation of light-emitting devices (LEDs), QD-LEDs have attracted deal attention displays lighting. To meet the commercial requirements, brightness needs be further improved. In this work, we propose multilayer heterostructures on SiO2 substrate, which provides multiple reflective bands with very efficiency nearly...

We demonstrate experimentally and numerically a method using the incoherent delayed self-interference (DSI) of chaotic light from semiconductor laser with optical feedback to generate wideband signal. The results show that, DSI can eliminate domination relaxation oscillation existing in therefore flatten widen power spectrum. Furthermore, depresses time-delay signature induced by external cavity modes improves symmetry probability distribution more than one magnitude. also that this signal...

We propose a method to locate precisely faults in wavelength-division-multiplexing (WDM) passive optical network (PON) by using wavelength tunable chaotic laser. The laser consists of multiple-longitudinal-mode Fabry-Perot (FP) diode whose modes match the channels WDM-PON, and an feedback loop including filter. feeds proportion light one mode that passes through filter back into cavity generate light. By adjusting frequency, we can tune light, diagnose corresponding branch WDM-PON....

We present a simple method to generate spectrally uniform wideband chaos by injecting chaotic laser into fiber ring resonator. The resonator is single-coupler equipped with an optical filter and amplifier, which adjust the field circulating in ring. incoherent interference of fields produces power spectrum density distribution. experimentally achieved that extends over 26.5 GHz (limited measurement bandwidth) fluctuates within ±1.5 dB. In addition, tuning frequency can control spectral...

Although previously reported terahertz absorbers can achieve high-sensitivity refractive index sensing, the resonant peak is too broad, which leads to a low figure of merit (FOM). Transmissive sensors based on bound states in continuum (BIC) high FOM, but they have some limitations sensitivity. Herein, we propose periodic triple parallel metal bars structure obtain quality, strong field, and multiple hot spots by Friedrich–Wintgen BIC. Numerical results show sensitivity FOM reach 1877...

Plasmon resonance plays an important role in improving the detection of biomolecules, and it is one focuses research to use metal plasmon achieve fluorescence enhancement improve sensitivity. However, problems nondynamic tuning quenching need be solved. Graphene surface can dynamically controlled, graphene adsorption fluorescent molecules avoid greatly emission intensity. The graphene-metal hybrid structure designed this work solve above two well, efficiency on sensitivity biological...

Wavelength division multiplexing (WDM) devices are key photonic integrated circuit (PIC) elements. Conventional WDM based on silicon waveguides and crystals have limited transmittance due to the high loss introduced by strong backward scattering from defects. In addition, it is challenging reduce footprint of those devices. Here we theoretically demonstrate a device in telecommunication range all-dielectric topological valley crystal (VPC) structures. We tune its effective refractive index...

Large normal-direction excitation and emission of dual-emitting quantum dots (QDs) are essential for practical application QD sensors based on the ratiometric fluorescence response. We have numerically demonstrated an all-dielectric four-layer cascaded photonic crystal (CPC) structure (alternating TiO2 SiO2/SU8 layers with two dimensional nanoscale patterns in each layer) which is capable providing high Q-factor leaky modes at wavelengths QDs low coinciding peaks a QD. Normal-direction...

Here we theoretically design valley photonic crystals (VPCs) based on two-dimensional (2D) hexagonal boron nitride (hBN) materials, which are able to support topological edge states in the visible region. The can achieve spin-dependent unidirectional transmission with a high forward transmittance up 0.96 and contrast of 0.99. We further study effect refractive index bandwidth, it is found that increase index, both bandwidth increased accordingly. This opens new possibilities designing...

Fano resonances in plasmonic nanostructures exhibit sharp resonance and strong light confinement. These properties are very useful for sensing applications, which rely on plasmon line shape engineering. clusters depend structure symmetry, this study provides a general understanding of with D2h symmetry. We show that, because the excitation B3u B2u dark subradiant modes, four kinds appear spectra hexamers When central particle is introduced to form heptamer, it shown aside from influence...

A new method to control heat flux, called thermal surface transformation (TST), is introduced from thermodynamics. Compared with thermodynamics, TST has many advantage. First, there no mathematical calculation during the whole process in (novel devices can be designed graphically a surface-to-surface way). Second, all of various functions, shapes and sizes by only require one homogenous anisotropic medium, i.e., thermal-null medium (TNM). With help effective theory, TNM realized layered...

Ultra-compact topological ring-resonators with chirality are important devices for quantum optics. However, there limited demonstrations of chiral resonators, especially in the visible region. We proposed a photonic ring-resonator based on hexagonal boron nitride (hBN) valley crystal (VPC). The spin-valley locking effect VPC allows achieving robust unidirectional transmission edge states region (600 nm-650 nm). As result, high quality factor (679.3) free spectral range 15.2 nm can be...

Abstract We show a hybrid structure consisting of Si film with photonic crystal surface and random triangular gold grooves reflector at the bottom, which is capable realizing efficient, broad-band, wide-angle optical absorption. It numerically demonstrated that enhanced absorption in broad wavelength range (0.3–9.9 μm) due to scattering effect both sides created resonance modes. Larger thickness period are favored enhance broader range. Substantial electric field concentrates film. Our...

NiO is a widely used p-type semiconductor. The desired optical and electrical properties of vary in different application fields. To modulate the NiO, nitrogen (N)-doped thin films were synthesized by reactive radio-frequency magnetron sputtering on ITO-coated glass substrates. influence substrate temperature was investigated. XRD studies indicated cubic structure. With increase temperature, average transmittance visible region gradually reduced from 90% to 50%. bandgap energy narrowed 3.5...

Here, we theoretically present an on-chip nanophotonic asymmetric transmission device (ATD) based on the photonic crystal (PhC) waveguide structure with complete bandgaps (CPBGs). The ATD comprises two-dimensional silica and germanium PhCs CPBGs, within which line defects are introduced to create highly efficient waveguides achieve high forward transmittance. In meantime, total internal reflection principle is applied block backward incidence, achieving transmission. We optimize design of by...