Optical analog signal processing has been gaining significant attention as a way to overcome the speed and energy limitations of digital techniques. Metasurfaces offer promising avenue towards this goal due their efficient manipulation optical signals over deeply subwavelength volumes. To date, metasurfaces have proposed transform in spatial domain, e.g., for beam steering, focusing, or holography, which angular-dependent responses, nonlocality, are unwanted features that must be avoided...

Image processing and edge detection are at the core of several newly emerging technologies, such as augmented reality, autonomous driving more generally object recognition. is typically performed digitally using integrated electronic circuits algorithms, implying fundamental size speed limitations, well significant power needs. On other hand, it can also be in a low-power analog fashion Fourier optics, requiring however bulky optical components. Here, we introduce dielectric metasurfaces...

Optical analog computing using metasurfaces has been the subject of numerous studies, aimed at implementing highly efficient and ultrafast image processing in a compact device. The proposed approaches to date have shown limitations terms spatial resolution, overall efficiency, polarization azimuthal angular dependence. Here, we present design polarization-insensitive metasurface with tailored nonlocality based on Fano resonant response, enabling both odd- even-order mathematical operations...

In recent years, parity-time ($P\phantom{\rule{0}{0ex}}T$) symmetry has been explored in several areas of physics, including quantum mechanics, optics, and acoustics. Now medicine can reap the benefits: Utilizing anisotropic transmission resonances supported by a $P\phantom{\rule{0}{0ex}}T$-symmetric structure, this study develops noninvasive glucose sensor operating microwave band. Analytical results full-wave simulations indicate that resonance shift be made fairly linear with respect to...

In this work, we experimentally demonstrate metasurface-enhanced photoresponse in organic photodetectors. We have designed and integrated a metasurface with broadband functionality into an photodetector, the goal of significantly increasing absorption light generated photocurrent from 560 up to 690 nm. discuss how can be fabrication photodiode. Our results show large gains responsivity 1.5× 2× between

With the ability to confine light subwavelength volumes, plasmonic nanostructures and metamaterials have proven be powerful tools for nanophotonic applications. For nonlinear processes, however, small dimensions of devices can become problematic, as phase-matching techniques—designed increase interaction lengths—are no longer applicable. In this work, we utilize field confining properties nanoparticles in a modified metal–insulator–metal (MIM) patch nanoantenna efficiently couple an...

We propose an approach to realize optically transparent microwave absorber based on water-based moth-eye metamaterial structures. The is made of a periodic array properly shaped glass caps infiltrated with distilled water. Analytical calculations and numerical simulations show that the absorbs electromagnetic waves over wide spectral band ranging from 4GHz well above 120GHz, showing absorption levels close 100% for incident radiation ranges normal grazing angles, both TE TM polarizations....

We demonstrate that arrays of hourglass-shaped nanopillars patterned into crystalline silicon substrates exhibit vibrant, highly controllable reflective structural coloration. Unlike structures with uniform sidewall profiles, the hourglass profile defines two separate regions on pillar: a head and body. The acts as suspended Mie resonator is responsible for resonant reflectance, while body to suppress broadband reflections from surface. combination these effects gives rise vibrant colors....

Organic light emitting diodes can achieve close to unitary internal quantum efficiency; however, their external efficiency is much lower due losses within the device. Gradient metasurfaces and metagratings be utilized substantial electromagnetic field manipulation enhancement of local density photonic states, thereby improving organic devices. In this work, we show how suitably designed reflecting plasmonic potentially incorporated into a top-emitting device, resulting in large emissivity by...

An ideal toolset to diagnose diabetes consists of an in-hand portable device that can effectively detect glucose concentration in the blood real time without having perforate skin. However, existing monitoring systems are invasive, and those noninvasive have low accuracy. Here, we explore alternative approach for blood. We excite Mie-like resonances within highly lossy media by introducing active loads, uniformly applied inner circumference a dielectric ring structure. Our study opens...

Broadband and omnidirectional absorption of electromagnetic waves is required in various technologies, such as stealth, high quality wireless communications, spacecraft shielding. In this study, we theoretically numerically study a graphene-based absorber achieving broadband from 4 GHz to 100 0 ∘ 50 ∼70 , with over 90% efficiency. By applying thin layer graphene upon SiO 2 moth-eye structure, show that can be effectively absorbed the structure optically transparent, ideal for civilian...

Ways to achieve highly efficient electromagnetic absorption over a broad bandwidth and angular spectrum have been discussed extensively in the past decades for various applications, such as low reflection devices energy harvesting. To satisfy efficiency requirements, metamaterial approaches explored recent years. In this context, most studies suggested use of frequency selective surfaces or arrays plasmonic resonators, which limit performance. Here, we explore application refractory Brewster...

A metasurface with appropriately designed transverse spatial inhomogeneities can provide the desired phase redistribution in response to an incident wave arbitrary angle. This property of gradient metasurfaces has been used modify light propagation unusual manners, transform impinging optical wavefront large flexibility. In this work, we show how be tailored offer high absorption thin absorptive layers, and design realistic for purpose using dielectric materials.

Operation of concentrated solar power receivers at higher temperatures (<700°C) would enable supercritical carbon dioxide (sCO2) cycles for improved cycle efficiencies (<50%) and cost-effective thermal power. Unfortunately, radiative losses in conventional can negatively impact the system efficiency gains. One approach to improve receiver is utilize selective coatings that enhance absorption across visible spectrum while minimizing emission infrared reduce losses. Existing coatings, however,...

We present Si-based metasurfaces with suitably engineered spatial dispersion and non-locality that can perform even odd mathematical operations on an input image, enabling all-analog signal processing on-the-fly edge detection.

Metasurfaces enable unusual manipulation of the impinging electromagnetic wavefront over a subwavelength thickness. One interesting opportunity that has been recently explored consists in possibility performing mathematical operations analog domain, with clear advantages terms speed and power consumption compared to digital approaches, footprint much smaller than classical computing approaches based on Fourier optics. In this context, multilayer structures photonic crystals have proposed...

We present experimental results on metasurfaces capable of performing analog image processing. Specifically, we show designs for 1st and 2nd order spatial differentiation enabling low power real-time edge detection. © 2019 The Author(s)

Metasurfaces enable a large degree of manipulation the impinging electromagnetic wavefront over thin profile. As an example, retroreflective metasurfaces reflect waves in opposite half space compared to regular mirrors, functionality highly desirable for identification tagging, radars and street signaling. While common approaches require bulky configurations, gradient have been recently proposed as retroreflectors. However, these designs suffer from inefficiencies sensitivity loss. Here, we...

The external quantum efficiency of organic light emitting devices is affected by losses within the devices. We show that seamless incorporation 2-dimensional reflecting metagratings structure can result in substantial changes and improvements emission characteristics. Quasiperiodic as well periodic have been included. With square lattice metagratings, enhancements surface-normal intensity (of up to 4.8x) observed relative a control device without metagrating. enhanced intensities normal...

Communication blackout of hypersonic flights refers to an interruption in communication when a flight enters extreme environment atmospheric gas ionization. Specifically, as the ionized and electron density goes over plasma density, medium becomes conductive, where conductivity can be translated into permittivity with negative real number. The resulting class material characterized ENG (Epsilon-Negative) material, which induces significant decaying constant absorbs or reflects most...