Barlowglud7307

Graphene plasmons, the electromagnetic waves coupled to charge excitations in a graphene sheet, have attracted great interest because of their intriguing properties, such as electrical tunability, long plasmon lifetime, and high degree of spatial confinement. click here They may enable the manufacture of novel optical devices with extremely high speed, low driving voltage, low power consumption and compact sizes. In this paper, we propose a graphene-based metasurface which can support a topologically protected graphene plasmon mode with the ability of ultrastrong field localization. We show that such a plasmonic metasurface, constructed by depositing a graphene sheet on a periodic silicon substrate, would exhibit different bandgap topological characteristics as the filling factor of the periodic substrate changes. By setting suitable Fermi levels of graphene at two different areas of the metasurface, topological interface plasmon modes can be excited, resulting in over 8 orders of magnitude enhancement of the plasmon intensity. The topologically protected plasmon mode is robust against the perturbation of the structural parameters, and its frequency can be tuned by adjusting the gate-voltage on the graphene sheet. This highly integrated platform could provide a pathway for low-power and actively controllable nonlinear optics.In this study, surface-enhanced Raman scattering (SERS) scheme is combined with localized surface plasmon resonance (LSPR) detection on a thin gold film with stripe patterns of gold nanoparticles (GNPs) via convective self-assembly (CSA) method. The potential of dual modal plasmonic substrates was evaluated by binding 4-ABT and IgG analytes, respectively. SERS experiments presented not only a high sensitivity with a detection limit of 4.7 nM and an enhancement factor of 1.34 × 105, but an excellent reproducibility with relative standard deviation of 5.5%. It was found from plasmonic sensing experiments by immobilizing IgG onto GNP-mediated gold film that detection sensitivity was improved by more than 211%, compared with a conventional bare gold film. Our synergistic SERS-LSPR approach based on a simple and cost-effective CSA method could open a route for sensitive, reliable and reproducible dual modal detection to expand the application areas.β-Ga2O3 is a new type of fast scintillator with potential applications in medical imaging and nuclear radiation detection with high count-rate situations. link2 Because of the severe total internal reflection with its high refractive index, the light extraction efficiency of β-Ga2O3 crystals is rather low, which would limit the performance of detection systems. In this paper, we use hollow nanosphere arrays with a high-index contrast to enhance the light extraction efficiency of β-Ga2O3 crystals. We can increase the transmission diffraction efficiency and reduce the reflection diffraction efficiency through controlling the refractive index and the thickness of the shell of the hollow nanospheres, which can lead to a significant increase in the light extraction efficiency. The relationships between the light extraction efficiency and the refractive index and thickness of the shell of the hollow nanospheres are investigated by both numerical simulations and experiments. It is found that when the refractive index of the shell of the hollow nanospheres is higher than that of β-Ga2O3, the light extraction efficiency is mainly determined by the diffraction efficiency of light transmitted from the surface with the hollow nanosphere arrays. When the refractive index of the shell is less than that of β-Ga2O3, the light extraction efficiency is determined by the ratio of the diffraction efficiency of the light transmitted from the surface with the hollow nanosphere arrays to the diffraction efficiency of the light that can escape from the lateral surface.Light-sheet fluorescence microscopy (LSFM) facilitates high temporal-spatial resolution, low photobleaching and phototoxicity for long-term volumetric imaging. However, when a high axial resolution or optical sectioning capability is required, the field of view (FOV) is limited. Here, we propose to generate a large FOV of light-sheet by scanning multiple focus-shifted Gaussian beam arrays (MGBA) while keeping the high axial resolution. The positions of the beam waists of the multiple Gaussian beam arrays are shifted in both axial and lateral directions in an optimized arranged pattern, and then scanned along the direction perpendicular to the propagation axis to form an extended FOV of light-sheet. Complementary beam subtraction method is also adopted to further improve axial resolution. Compared with the single Gaussian light-sheet method, the proposed method extends the FOV from 12 μm to 200 μm while sustaining the axial resolution of 0.73 μm. Both numerical simulation and experiment on samples are performed to verify the effectiveness of the method.Conventional three-dimensional (3D) holography based on recording interference fringes on a photosensitive material usually has unavoidable zero-order light, which merges with the holographic image and blurs it. Off-axis design is an effective approach to avoid this problem; however, it in turn leads to the waste of at least half of the imaging space for holographic reconstruction. Herein, we propose an on-axis 3D holography based on Malus-assisted metasurfaces, which can eliminate the zero-order light and project the holographic image in the full transmission space. Specifically, each nanostructure in the metasurface acts as a nano-polarizer, which can modulate the polarization-assisted amplitude of incident light continuously, governed by Malus law. By carefully choosing the orientation angles of nano-polarizers, the amplitude can be both positive and negative, which can be employed to extinct zero-order light without affecting the intensity modulation for holographic recording. We experimentally demonstrate this concept by projecting an on-axis 3-layer holographic images in the imaging space and all experimental results agree well with our prediction. Our proposed metasurface carries unique characteristics such as ultracompactness, on-axis reconstruction, extinction of zero-order light and broadband response, which can find its market in ultracompact and high-density holographic recording for 3D objects.The motion law of complex fluids under extreme conditions is an important aspect of high energy density physics research. It has been demonstrated that using multi-channel curved crystals and a framing camera to observe the laser-produced target pellets doped with tracer elements is an appropriate method for investigating this law. This paper presents a feasible design scheme for a multi-channel toroidal imager, with the ray trace model used to verify the rationality of the evaluation method and the aberration of single toroidal crystal imaging. We demonstrate that the field of view (FOV) consistency of the four-channel Ge(400) toroidal crystal imager is less than 50 µm, while the best spatial resolution is ∼4 µm and the FOV of each channel is >2.2 mm.We present the results from a Monte Carlo computer simulation of adaptive optics (AO) pre-compensated laser uplink propagation through the Earth's atmospheric turbulence from the ground to orbiting satellites. The simulation includes the so-called point-ahead angle and tests several potential AO mitigation modes such as tip/tilt or full AO from the downlink beam, and a laser guide star at the point ahead angle. The performance of these modes, as measured by metrics relevant for free-space optical communication, are compared with no correction and perfect correction. The aim of the study is to investigate fundamental limitations of free-space optical communications with AO pre-compensation and a point-ahead angle, therefore the results represent an upper bound of AO corrected performance, demonstrating the potential of pre-compensation technology. Performance is assessed with varying launch aperture size, wavelength, launch geometry, ground layer turbulence strength (i.e. day/night), elevation angle and satellite orbit (Low-Earth and Geostationary). By exploring this large parameter space we are able examine trends on performance with the aim of informing the design of future optical ground stations and demonstrating and quantifying the potential upper bounds of adaptive optics performance in free-space optical communications.A highly compact hyperspectral imager with an automatic geometric rectification function is developed in this study, which can be mounted on a UAV for ultra-wide range hyperspectral imaging. For better application, the system can provide visible light image transmission and hyperspectral imaging in the real-time mode. A specific design is proposed to allow the visible light camera and hyperspectral camera to share the same telescope optical path, making the system have a high integration level with a total mass of 1.9 kilograms. Thanks to the sharing-optical-path design, the field of view (FOV), frame rate, and spatial resolution are modified the same between the visible light camera and hyperspectral camera. As a result, the geometric rectification is easily performed, and repeated rectifications are eliminated to improve the imaging efficiency. A FOV of 40 degrees in the frame direction and 26 degrees in the flight direction are realized with a focal length of 13mm, providing a large spectral range from 400 nm to 1000 nm and an excellent spectral resolution of 2.5 nm. An automatic geometric rectification workflow is presented and verified in experiments, which can improve the geometric rectification of hyperspectral images in the presence of low-quality UAV navigation data through the incorporation of frame images. Experimental results show that the relative accuracy of geometric rectification is less than 2 pixels when applying the algorithm to our system dataset.Exceptional points (EPs) could potentially enhance the sensitivity of an optical sensing system by orders of magnitude. Higher-order EP systems, having more complex physics, can further boost this parameter. In this paper, we investigate the response order of high-order non-Hermitian systems and provide a guideline for designing a sensor with high response order. Based on this design rule, we propose and demonstrate an optical sensor with a fourth-order response, and analyze its associated properties. The four resonant wavelengths of our optical sensor simultaneously collapse at a high-order exceptional point in the parameter space, providing a fourth root relation between the amount of wavelength splitting and the amplitude of the perturbation. A large sensitivity enhancement factor over 100, is observed when the wavelength splitting is compared with traditional single resonator-based sensors under small perturbation conditions.Achieving a high Q-factor metamaterial unit for a precision sensing application is highly demanded in recent years, and most of the developed high-performance sensors based on the high-Q metamaterial units are due to the dielectric/magnetic property changes of the substrate/superstrate. In this paper, we propose a completely different sensing metamaterial unit configuration, with good sensing sensitivity and precision properties, based on the thermally tunable liquid metals. Specifically, a basic thermally tunable metamaterial unit, the mercury-inspired split ring resonator (SRR), is firstly presented to theoretically show the magnetic resonance and negative permeability frequency band shift properties under different background temperatures. link3 Then, considering the radiation loss mechanism of the conventional SRR metamaterial unit and based on the physically reliable ability of liquid metals, the modified mercury-inspired Fano and toroidal resonators with a large frequency tuning range and high Q-factor are developed and discussed.