scholarly journals Realization of Ultrathin Waveguides by Elastic Metagratings

2021 ◽  
Author(s):  
Yabin Hu ◽  
Yunhao Zhang ◽  
Guangyuan Su ◽  
Meiying Zhao ◽  
Bing Li ◽  
...  
Keyword(s):  
Incident Angle ◽  
Slab Waveguide ◽  
Edge States ◽  
Wave Trapping ◽  
Compact Size ◽  
Wide Range ◽  
Waveguide Model ◽  
Classical Waves ◽  
Uniform Medium ◽  
Design Paradigm

Abstract Guiding transports of classical waves has inspired a wealth of nontrivial physics and momentous applications in a wide range of fields. To date, a robust and compact way to guide energy flux travelling along an arbitrary, prescheduled trajectory in a uniform medium is still a fundamental challenge. Here we propose and experimentally realize a generic framework of ultrathin waveguides for full-angle wave trapping and routing. The metagrating-based waveguide can totally suppress all high-order parasitic diffractions to efficiently route guided elastic waves without leakage. Remarkably, the proposed waveguide protype works in a broad frequency range from 12 to 18 kHz and regardless of the incident angle. An analytical slab-waveguide model is further presented to predict and tailor the diffracted patterns in the metagrating-based waveguide. Compared with existing methods based on topological edge states or defected metamaterials, our meta-waveguide strategy exhibits absolute advantages in compact size, robust performance, and easy fabrication, which may provide a new design paradigm for vibration control in solids, wave steering in electromagnetics, acoustics and other waves.

scholarly journals Suppressing meta-holographic artifacts by laser coherence tuning

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Yaniv Eliezer ◽  
Geyang Qu ◽  
Wenhong Yang ◽  
Yujie Wang ◽  
Hasan Yılmaz ◽  
...  
Keyword(s):  
Spatial Coherence ◽  
Fine Tuning ◽  
Total Power ◽  
Image Sharpness ◽  
Continuous Tuning ◽  
Fine Spatial Resolution ◽  
Compact Size ◽  
Wide Range ◽  
Fabrication Defects ◽  
Holographic Displays

AbstractA metasurface hologram combines fine spatial resolution and large viewing angles with a planar form factor and compact size. However, it suffers coherent artifacts originating from electromagnetic cross-talk between closely packed meta-atoms and fabrication defects of nanoscale features. Here, we introduce an efficient method to suppress all artifacts by fine-tuning the spatial coherence of illumination. Our method is implemented with a degenerate cavity laser, which allows a precise and continuous tuning of the spatial coherence over a wide range, with little variation in the emission spectrum and total power. We find the optimal degree of spatial coherence to suppress the coherent artifacts of a meta-hologram while maintaining the image sharpness. This work paves the way to compact and dynamical holographic displays free of coherent defects.

scholarly journals A Nanoplasmonic-Based Biosensing Approach for Wide-Range and Highly Sensitive Detection of Chemicals

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1961
Author(s):  
Francesco Arcadio ◽  
Luigi Zeni ◽  
Aldo Minardo ◽  
Caterina Eramo ◽  
Stefania Di Di Ronza ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Limit Of Detection ◽  
Slab Waveguide ◽  
Grating Pattern ◽  
Transparent Substrate ◽  
Synthetic Receptor ◽  
Sensing Applications ◽  
Wide Range ◽  
Plastic Optical Fibers ◽  
Highly Sensitive Detection

In a specific biosensing application, a nanoplasmonic sensor chip has been tested by an experimental setup based on an aluminum holder and two plastic optical fibers used to illuminate and collect the transmitted light. The studied plasmonic probe is based on gold nanograting, realized on the top of a Poly(methyl methacrylate) (PMMA) chip. The PMMA substrate could be considered as a transparent substrate and, in such a way, it has been already used in previous work. Alternatively, here it is regarded as a slab waveguide. In particular, we have deposited upon the slab surface, covered with a nanograting, a synthetic receptor specific for bovine serum albumin (BSA), to test the proposed biosensing approach. Exploiting this different experimental configuration, we have determined how the orientation of the nanostripes forming the grating pattern, with respect to the direction of the input light (longitudinal or orthogonal), influences the biosensing performances. For example, the best limit of detection (LOD) in the BSA detection that has been obtained is equal to 23 pM. Specifically, the longitudinal configuration is characterized by two observable plasmonic phenomena, each sensitive to a different BSA concentration range, ranging from pM to µM. This aspect plays a key role in several biochemical sensing applications, where a wide working range is required.

Incident-angle-controlled semitransparent colored perovskite solar cells with improved efficiency exploiting a multilayer dielectric mirror

Nanoscale ◽  
2017 ◽  
Vol 9 (37) ◽  
pp. 13983-13989 ◽  
Author(s):  
Kyu-Tae Lee ◽  
Ji-Yun Jang ◽  
Sang Jin Park ◽  
Song Ah Ok ◽  
Hui Joon Park
Keyword(s):  
Solar Cells ◽  
Visible Light ◽  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Incident Angle ◽  
Power Conversion ◽  
Perovskite Solar Cells ◽  
Dielectric Mirror ◽  
Wide Range ◽  
Multilayer Dielectric

See-through colored perovskite solar cells that exploit a dielectric mirror are demonstrated. The dielectric mirror strongly reflects a wide range of visible light back to a photoactive layer for efficient light-harvesting, yielding 10.12% power conversion efficiency, with iridescent semitransparent colors.

scholarly journals An Ultra-Wideband THz/IR Metamaterial Absorber Based on Doped Silicon

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2590 ◽  
Author(s):  
Huafeng Liu ◽  
Kai Luo ◽  
Shihao Tang ◽  
Danhua Peng ◽  
Fangjing Hu ◽  
...  
Keyword(s):  
Incident Angle ◽  
Average Power ◽  
Far Infrared ◽  
Metamaterial Absorber ◽  
Ultra Wideband ◽  
Broadband Absorption ◽  
Wide Range ◽  
Doped Silicon ◽  
Simulated Field ◽  
Underlying Mechanisms

Metamaterial-based absorbers have been extensively investigated in the terahertz (THz) range with ever increasing performances. In this paper, we propose an all-dielectric THz absorber based on doped silicon. The unit cell consists of a silicon cross resonator with an internal cross-shaped air cavity. Numerical results suggest that the proposed absorber can operate from THz to far-infrared regimes, having an average power absorption of ∼95% between 0.6 and 10 THz. Experimental results using THz time-domain spectroscopy show a good agreement with simulations. The underlying mechanisms for broadband absorption are attributed to the combined effects of multiple cavities modes formed by silicon resonators and bulk absorption in the doped silicon substrate, as confirmed by simulated field patterns and calculated diffraction efficiency. This ultra-wideband absorption is polarization insensitive and can operate across a wide range of the incident angle. The proposed absorber can be readily integrated into silicon-based photonic platforms and used for sensing, imaging, energy harvesting and wireless communications applications in the THz/IR range.

MEASUREMENT OF THE SURFACE CONDITION OF A THERMALLY SPRAYED MATERIAL AND ITS THREE-DIMENSIONAL POSITION USING A LASER RANGEFINDER

2008 ◽  
Vol 22 (11) ◽  
pp. 887-892
Author(s):  
KOZO OHTANI ◽  
YOSHIKO SHINHARA ◽  
MITSUO KIDO ◽  
MITSURU BABA
Keyword(s):  
Control Function ◽  
Incident Angle ◽  
Surface Condition ◽  
Three Dimensional ◽  
Image Sensor ◽  
Prototype System ◽  
Laser Rangefinder ◽  
Position Measurement ◽  
Wide Range ◽  
Thermally Sprayed

This paper describes that a measurement method for the surface condition of a thermally sprayed object and its three dimensional position with a laser rangefinder. The feature of this rangefinder is to equip an image sensor which has the ability of simultaneously detecting the position of a light and the incident angle onto the sensor. Moreover, the sensor has an autonomous exposure time control function. Therefore, our laser rangefinder can detect the 3D positions of an object with unknown reflectance. We constructed the prototype system and did some experiments to verify the proposed method. The error of the 3D position measurement was Δ z / z =0.7%. As concerns the detection of the surface condition, we could identify three types of surface roughness of a measured object with accuracy. The proposed method has great potential for a wide range of industrial inspections.

scholarly journals Optical Filter with Large Angular Dependence of Transmittance Using Liquid Crystal Devices

Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1199
Author(s):  
Kohki Takatoh ◽  
Masahiro Ito ◽  
Suguru Saito ◽  
Yuuta Takagi
Keyword(s):  
Liquid Crystal ◽  
Incident Angle ◽  
Optical Filter ◽  
Half Wave Plate ◽  
S Waves ◽  
Wave Plate ◽  
Liquid Crystal Devices ◽  
Half Wave ◽  
Wide Range ◽  
Pretilt Angles

This study proposed a new type of optical device with variable transmittance based on the incident angle direction. These devices consist of two liquid crystal devices (LCDs) with a half-wave plate between them. Hybrid aligned nematic (HAN)-type guest-host (GH) LCDs or GH-LCDs with antiparallel alignment of high pretilt angles were used. The use of a half-wave plate allowed for the control of the p- and s-waves. Using these devices, a wide range of transmittances were obtained because no polarizer was used. The newly proposed LCDs have a wide range of applications, including use on buildings, vehicles, and glasses.

scholarly journals Dimmable High Power LED Driver Using Fuzzy Logic Controller

2021 ◽  
Vol 5 (2) ◽  
pp. 45
Author(s):  
Rizky Fatur Rochman ◽  
Eka Prasetyono ◽  
Rachma Prilian Eviningsih
Keyword(s):  
Fuzzy Logic ◽  
Fuzzy Logic Controller ◽  
Constant Current ◽  
Led Driver ◽  
Flyback Converter ◽  
Compact Size ◽  
Wide Range ◽  
Driver Circuit ◽  
Converter Topology ◽  
Lighting Loads

The use of lighting loads is one of the crucial matters which increases every year. The increasing use then leads to the development of brighter and longer-lasting sources. In addition, the conventional use of lighting loads today, which only emit light at its maximum intensity, does not allow the consumers to adjust the brightness level as needed. Consequently, this condition may cause energy wastage. The LED lighting system is gaining popularity as it is widely used in a wide range of applications. The advantages of LEDs, such as its compact size and varied lamp colors, replace conventional lighting sources. The linear setting of the driver topology using the flyback converter was aimed to control the LEDs with a constant current in order to adjust the variation of the LED light intensity. The closed-loop driver circuit with flyback converter topology was designed as an LED driver with a given load specification from the LED string. A dimmable feature was included for adjusting the intensity of the light produced by the LEDs. Eventually, the fuzzy logic controller (FLC) method was applied to the integrated change setting to obtain a dynamic response.

scholarly journals Review on Pressure Sensors: A Perspective from Mechanical to Micro-electro-mechanical systems

2021 ◽  
Author(s):  
Ankur Gupta
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Pressure Sensors ◽  
Micro Electro Mechanical System ◽  
Single Chip ◽  
Micro Electro Mechanical Systems ◽  
Compact Size ◽  
Wide Range ◽  
Fabrication Procedure ◽  
Application Requirements

Swiftly emerging research prospects in the Micro-Electro-Mechanical System (MEMS) enable to build of complex and sophisticated microstructures on a substrate containing moving masses, cantilevers, flexures, levers, linkages, dampers, gears, detectors, actuators, and many more on a single chip. One of the MEMS initial products that emerged into the micro-system technology is the MEMS pressure sensor. Because of their high performance, low cost, and compact size, these sensors are extensively being adopted in numerous applications viz., aerospace, automobile, and bio-medical domain, etc. These application requirements drive and impose tremendous conditions on sensor design to overcome the tedious design and fabrication procedure before its reality. MEMS-based pressure sensors enable a wide range of pressure measurements as per the application requirements. Considering its vast utility in industries, this paper presents a detailed review of MEMS-based pressure sensors and their wide area of applications, their design aspects, and challenges, to provide state of an art gist to the researchers of a similar domain in one place.

scholarly journals Machine–learning-enabled metasurface for direction of arrival estimation

Nanophotonics ◽  
2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Min Huang ◽  
Bin Zheng ◽  
Tong Cai ◽  
Xiaofeng Li ◽  
Jian Liu ◽  
...  
Keyword(s):  
Machine Learning ◽  
Incident Angle ◽  
Wide Band ◽  
Direction Of Arrival ◽  
Doa Estimation ◽  
Signal Acquisition ◽  
Reconstruction Algorithms ◽  
Time Saving ◽  
Wide Range

Abstract Metasurfaces, interacted with artificial intelligence, have now been motivating many contemporary research studies to revisit established fields, e.g., direction of arrival (DOA) estimation. Conventional DOA estimation techniques typically necessitate bulky-sized beam-scanning equipment for signal acquisition or complicated reconstruction algorithms for data postprocessing, making them ineffective for in-situ detection. In this article, we propose a machine-learning-enabled metasurface for DOA estimation. For certain incident signals, a tunable metasurface is controlled in sequence, generating a series of field intensities at the single receiving probe. The perceived data are subsequently processed by a pretrained random forest model to access the incident angle. As an illustrative example, we experimentally demonstrate a high-accuracy intelligent DOA estimation approach for a wide range of incident angles and achieve more than 95% accuracy with an error of less than 0.5 ° $0.5{\degree}$ . The reported strategy opens a feasible route for intelligent DOA detection in full space and wide band. Moreover, it will provide breakthrough inspiration for traditional applications incorporating time-saving and equipment-simplified majorization.

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