scholarly journals Broadband wavelength demultiplexer using Fano-resonant metasurface

Nanophotonics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1015-1022
Author(s):  
Sang-Eun Mun ◽  
Chulsoo Choi ◽  
Jongwoo Hong ◽  
Byoungho Lee
Keyword(s):  
Optical Sensors ◽  
Fano Resonance ◽  
Near Infrared ◽  
Infrared Region ◽  
Proof Of Concept ◽  
Amplitude Control ◽  
Complete Control ◽  
Wide Range ◽  
Simulation And Experiment ◽  
Design Freedom

AbstractFano resonance, one of the interesting resonance phenomena in physics, provides versatile applications when combined with a concept of metasurface in nanophotonics. Fano-resonant metasurface (FRM) is attracting a lot of attention due to its superior narrowband characteristics as well as design freedom of metasurfaces in nanoscale. However, only the control of apparent asymmetric spectral nature of Fano resonance has been focused at applications such as optical sensors, as the amplitude feature of Fano resonances is relatively easy to control and can be measured by an experimental setup. Here, a method for modulating the phase information of FRM by both simulation and experiment is demonstrated. As a proof of concept, an optical demultiplexer, which can divide four target wavelengths in different directions of free space, is verified experimentally. It covers a broadband wavelength range of more than 350 nm in the near-infrared region with extremely small full-width at half-maximum. This approach can offer the complete control of FRM for a wide range of applications, including optical multiplexers, routers, filters, and switches, beyond conventional applications that have been limited to the amplitude control of Fano resonance.

scholarly journals Spectroscopic detection of forest diseases: a review (1970–2020)

2021 ◽  
Author(s):  
Lorenzo Cotrozzi
Keyword(s):  
Early Detection ◽  
Optical Sensors ◽  
Near Infrared ◽  
Sustainable Forest Management ◽  
Visible Spectrum ◽  
Cost Effective ◽  
Infrared Region ◽  
Forest Disturbances ◽  
Effective Manner ◽  
Forest Diseases

AbstractSustainable forest management is essential to confront the detrimental impacts of diseases on forest ecosystems. This review highlights the potential of vegetation spectroscopy in improving the feasibility of assessing forest disturbances induced by diseases in a timely and cost-effective manner. The basic concepts of vegetation spectroscopy and its application in phytopathology are first outlined then the literature on the topic is discussed. Using several optical sensors from leaf to landscape-level, a number of forest diseases characterized by variable pathogenic processes have been detected, identified and quantified in many country sites worldwide. Overall, these reviewed studies have pointed out the green and red regions of the visible spectrum, the red-edge and the early near-infrared as the spectral regions most sensitive to the disease development as they are mostly related to chlorophyll changes and symptom development. Late disease conditions particularly affect the shortwave-infrared region, mostly related to water content. This review also highlights some major issues to be addressed such as the need to explore other major forest diseases and geographic areas, to further develop hyperspectral sensors for early detection and discrimination of forest disturbances, to improve devices for remote sensing, to implement long-term monitoring, and to advance algorithms for exploitation of spectral data. Achieving of these goals will enhance the capability of vegetation spectroscopy in early detection of forest stress and in managing forest diseases.

scholarly journals Proximal Methods for Plant Stress Detection Using Optical Sensors and Machine Learning

Biosensors ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 193
Author(s):  
Alanna V. Zubler ◽  
Jeong-Yeol Yoon
Keyword(s):  
Machine Learning ◽  
Optical Sensors ◽  
Near Infrared ◽  
Plant Stress ◽  
Machine Learning Algorithms ◽  
Machine Learning Techniques ◽  
Detection Methods ◽  
Stress Detection ◽  
Recent Advances ◽  
Wide Range

Plant stresses have been monitored using the imaging or spectrometry of plant leaves in the visible (red-green-blue or RGB), near-infrared (NIR), infrared (IR), and ultraviolet (UV) wavebands, often augmented by fluorescence imaging or fluorescence spectrometry. Imaging at multiple specific wavelengths (multi-spectral imaging) or across a wide range of wavelengths (hyperspectral imaging) can provide exceptional information on plant stress and subsequent diseases. Digital cameras, thermal cameras, and optical filters have become available at a low cost in recent years, while hyperspectral cameras have become increasingly more compact and portable. Furthermore, smartphone cameras have dramatically improved in quality, making them a viable option for rapid, on-site stress detection. Due to these developments in imaging technology, plant stresses can be monitored more easily using handheld and field-deployable methods. Recent advances in machine learning algorithms have allowed for images and spectra to be analyzed and classified in a fully automated and reproducible manner, without the need for complicated image or spectrum analysis methods. This review will highlight recent advances in portable (including smartphone-based) detection methods for biotic and abiotic stresses, discuss data processing and machine learning techniques that can produce results for stress identification and classification, and suggest future directions towards the successful translation of these methods into practical use.

scholarly journals Research on Fano Resonance Sensing Characteristics Based on Racetrack Resonant Cavity

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1359
Author(s):  
Yaxin Yu ◽  
Jiangong Cui ◽  
Guochang Liu ◽  
Rongyu Zhao ◽  
Min Zhu ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Fano Resonance ◽  
Near Infrared ◽  
Resonant Cavity ◽  
High Sensitivity ◽  
Infrared Region ◽  
Optical Integrated Circuits ◽  
Element Simulation ◽  
Metal Insulator Metal ◽  
Sensing Characteristics

To reduce the loss of the metal–insulator–metal waveguide structure in the near-infrared region, a plasmonic nanosensor structure based on a racetrack resonant cavity is proposed herein. Through finite element simulation, the transmission spectra of the sensor under different size parameters were analyzed, and its influence on the sensing characteristics of the system was examined. The analysis results show that the structure can excite the double Fano resonance, which has a distinctive dependence on the size parameters of the sensor. The position and line shape of the resonance peak can be adjusted by changing the key parameters. In addition, the sensor has a higher sensitivity, which can reach 1503.7 nm/RIU when being used in refractive index sensing; the figure of merit is 26.8, and it can reach 0.75 nm/°C when it is used in temperature sensing. This structure can be used in optical integrated circuits, especially high-sensitivity nanosensors.

scholarly journals Wide Range Refractive Index Sensor Using a Birefringent Optical Fiber

2021 ◽  
Author(s):  
Moutusi De ◽  
Vinod Kumar Singh
Keyword(s):  
Refractive Index ◽  
Near Infrared ◽  
High Sensitivity ◽  
Infrared Region ◽  
Device Fabrication ◽  
Refractive Index Sensor ◽  
Potential Candidate ◽  
Wide Range ◽  
Analyte Detection ◽  
Birefringent Optical Fiber

Abstract In this article, an efficient high birefringent D-shaped photonic crystal fiber (HB-D-PCF) plasmonic refractive index sensor is reported. It is able to work over a long low refractive index (RI) analyte range from 1.29 to 1.36. This modified simple structured hexagonal PCF has high birefringence in the near-infrared region. A thin gold film protected by a titanium dioxide (TiO2) layer is deposited on the D-surface of the PCF which acts as surface plasmon active layer. The sensor consists of an analyte channel on the top of the fiber. The performance of the HB-D-PCF is analyzed based on finite element method (FEM). Both wavelength and amplitude interrogation techniques are applied to study the sensing performance of the optimized sensor. Numerical results show wavelength and amplitude sensitivity of 9245nm/RIU and 1312 RIU-1 respectively with high resolution. Owing to the high sensitivity, long range sensing ability as well as spectral stability the designed HB-D-PCF SPR sensor is a potential candidate for water pollution control, glucose concentration testing, biochemical analyte detection as well as portable device fabrication.

Crystallization and Optical Properties of Sr3Al2O6-SrAl2O4 Eutectic Glass

2018 ◽  
Vol 281 ◽  
pp. 163-168
Author(s):  
Jia Xi Liu ◽  
Nan Lu ◽  
Gang He ◽  
Xiao Yu Li ◽  
Jian Qiang Li ◽  
...  
Keyword(s):  
Near Infrared ◽  
Glass Ceramics ◽  
Photo Luminescence ◽  
Phase Evolution ◽  
Optical Transmittance ◽  
Infrared Region ◽  
Treatment Temperature ◽  
Glass Beads ◽  
Heat Treated ◽  
Wide Range

SrO-Al2O3 ceramics has prospective applications due to its photo-luminescence and persistent afterglow properties. Sr3Al2O6-SrAl2O4 eutectic glass was prepared by using the aerodynamic levitator equipped with a CO2 laser device. The prepared Sr3Al2O6-SrAl2O4 eutectic glass beads were further heat-treated at temperature from 880°C to 980°C. The phase evolution, crystallization behavior, optical transmittance and mechanical properties of the annealed eutectic glass ceramics were investigated. The as-prepared glass is colorless and transparent over a wide range from ultraviolet to near-infrared region, and the average in-line transmittance is over 80% in the range of 260-3200nm. There were two crystal phases Sr3Al2O6 and SrAl2O4 crystallized from the glass beads. With increasing heat-treatment temperature, the transparency of the samples decreased, and the hardness increased. The prepared Sr3Al2O6-SrAl2O4 eutectic glass and glass ceramics may be a promising candidate for the development of photo-luminescence and persistent afterglow materials.

scholarly journals A Straightforward Substitution Strategy to Tune BODIPY Dyes Spanning the Near-Infrared Region via Suzuki–Miyaura Cross-Coupling

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1297 ◽  
Author(s):  
Guanglei Li ◽  
Yu Otsuka ◽  
Takuya Matsumiya ◽  
Toshiyuki Suzuki ◽  
Jianye Li ◽  
...  
Keyword(s):  
Near Infrared ◽  
Cross Coupling ◽  
Cumulus Cells ◽  
Infrared Region ◽  
Quantum Yields ◽  
Nir Dyes ◽  
Wide Range ◽  
One Step ◽  
The One ◽  
First Time

In this study, a series of new red and near-infrared (NIR) dyes derived from 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) were developed by introducing thiophene and its derivatives to the 3- and 5- positions of the dichloroBODIPY core. For the first time, cyclictriol boronates and N-methyliminodiacetic acid (MIDA) boronate were used as organoboron species to couple with 3,5-dichloroBODIPY via the one-step Suzuki–Miyaura cross-coupling. Six kinds of thieno-expended BODIPY dyes were synthesized in acceptable yields ranging from 31% to 79%. All six dyes showed different absorption and emission wavelengths spanning a wide range (c.a. 600–850 nm) in the red and NIR regions with relatively high quantum yields (19–85%). Cellular imaging of 8-(2,6-dimethylphenyl)-re3,5-di(2-thienyl)-BODIPY (dye 1) was conducted using bovine cumulus cells, and the fluorescence microscopy images indicated that the chromophore efficiently accumulated and was exclusively localized in the cytoplasm, suggesting it could be utilized as a subcellular probe. All six dyes were characterized using 1H-NMR and mass spectrometry.

scholarly journals Methane emissions from dairies in the Los Angeles Basin

2017 ◽  
Vol 17 (12) ◽  
pp. 7509-7528 ◽  
Author(s):  
Camille Viatte ◽  
Thomas Lauvaux ◽  
Jacob K. Hedelius ◽  
Harrison Parker ◽  
Jia Chen ◽  
...  
Keyword(s):  
Los Angeles ◽  
Near Infrared ◽  
Atmospheric Transport ◽  
Infrared Region ◽  
Top Down ◽  
Ch4 Emissions ◽  
Eddy Simulation ◽  
Wide Range ◽  
The Fourier Transform ◽  
Southern California Region

Abstract. We estimate the amount of methane (CH4) emitted by the largest dairies in the southern California region by combining measurements from four mobile solar-viewing ground-based spectrometers (EM27/SUN), in situ isotopic 13∕12CH4 measurements from a CRDS analyzer (Picarro), and a high-resolution atmospheric transport simulation with a Weather Research and Forecasting model in large-eddy simulation mode (WRF-LES). The remote sensing spectrometers measure the total column-averaged dry-air mole fractions of CH4 and CO2 (XCH4 and XCO2) in the near infrared region, providing information on total emissions of the dairies at Chino. Differences measured between the four EM27/SUN ranged from 0.2 to 22 ppb (part per billion) and from 0.7 to 3 ppm (part per million) for XCH4 and XCO2, respectively. To assess the fluxes of the dairies, these differential measurements are used in conjunction with the local atmospheric dynamics from wind measurements at two local airports and from the WRF-LES simulations at 111 m resolution. Our top-down CH4 emissions derived using the Fourier transform spectrometers (FTS) observations of 1.4 to 4.8 ppt s−1 are in the low end of previous top-down estimates, consistent with reductions of the dairy farms and urbanization in the domain. However, the wide range of inferred fluxes points to the challenges posed by the heterogeneity of the sources and meteorology. Inverse modeling from WRF-LES is utilized to resolve the spatial distribution of CH4 emissions in the domain. Both the model and the measurements indicate heterogeneous emissions, with contributions from anthropogenic and biogenic sources at Chino. A Bayesian inversion and a Monte Carlo approach are used to provide the CH4 emissions of 2.2 to 3.5 ppt s−1 at Chino.

New insights into sensors based on radical bisphthalocyanines

2009 ◽  
Vol 13 (11) ◽  
pp. 1159-1167 ◽  
Author(s):  
María Luz Rodriguez-Méndez ◽  
Mónica Gay ◽  
J. Antonio de Saja
Keyword(s):  
Thin Films ◽  
Optical Sensors ◽  
Near Infrared ◽  
Electrochemical Sensors ◽  
Color Change ◽  
Charge Transfer Band ◽  
Infrared Region ◽  
Electrical Measurements ◽  
Sensing Applications ◽  
The Rich

The unique semiconducting, optical and electrochemical properties of radical lanthanide bisphthalocyanines make them ideal materials for sensing applications. A variety of chemical sensors have been developed using rare-earth bisphthalocyanine thin films. In this paper, the characteristics of sensors based on bisphthalocyanines are reviewed. The advantages of these sensors with respect to sensors developed using other metallophthalocyanines are discussed. Resistive sensors based on bisphthalocyanines change their conductivity when exposed to a variety of pollutant gases and volatile organic compounds. Because bisphthalocyanines are intrinsic semiconductors, the conductivity of their thin films is higher than the conductivity of metallophthalocyanine thin films. This facilitates the electrical measurements and enhances the sensitivity of the sensors. Optical sensors have also been developed based on the rich optical properties shown by bisphthalocyanines. Films characterized by a bright green color change to red or to blue upon oxidation or reduction. The changes also affect the charge-transfer band associated to the free radical that bisphthalocyanines show in the near infrared region. This band coincides with telecommunication wavelengths, making possible the fabrication of fiber optic sensors where a phthalocyanine film is deposited at one of the ends of the fiber. Electrochemical sensors have been developed taking advantage of the unique electrochemical behavior associated to the one-electron oxidation and one-electron reduction of the phthalocyanine ring. These reversible processes are extremely sensitive to the nature of the electrolytic solution. This has made possible the development of voltammetric sensors able to produce particular signals when immersed in different liquids. In the last part of the paper, the fundamentals and performance characteristics of electronic noses and electronic tongues based on bisphthalocyanines are described. Such devices have been successfully exploited in quality control, classification, freshness evaluation and authenticity assessment of a variety of food, mainly wines and olive oils.

scholarly journals Multiple Fano Resonance Excitation of All-Dielectric Nanoholes Cuboid Arrays in Near Infrared Region

2021 ◽  
pp. 104569
Author(s):  
Shilin Yu ◽  
Hao Li ◽  
Yusen Wang ◽  
Ziang Gao ◽  
Tonggang Zhao ◽  
...  
Keyword(s):  
Fano Resonance ◽  
Near Infrared ◽  
Infrared Region ◽  
Resonance Excitation ◽  
Near Infrared Region

scholarly journals In and Ga Codoped ZnO Film as a Front Electrode for Thin Film Silicon Solar Cells

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Duy Phong Pham ◽  
Huu Truong Nguyen ◽  
Bach Thang Phan ◽  
Thi My Dung Cao ◽  
Van Dung Hoang ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Solar Cells ◽  
Near Infrared ◽  
Infrared Region ◽  
Silicon Solar Cells ◽  
Zno Film ◽  
Thin Film Silicon ◽  
Wide Range ◽  
Transparent Conducting Electrodes

Doped ZnO thin films have attracted much attention in the research community as front-contact transparent conducting electrodes in thin film silicon solar cells. The prerequisite in both low resistivity and high transmittance in visible and near-infrared region for hydrogenated microcrystalline or amorphous/microcrystalline tandem thin film silicon solar cells has promoted further improvements of this material. In this work, we propose the combination of major Ga and minor In impurities codoped in ZnO film (IGZO) to improve the film optoelectronic properties. A wide range of Ga and In contents in sputtering targets was explored to find optimum optical and electrical properties of deposited films. The results show that an appropriate combination of In and Ga atoms in ZnO material, followed by in-air thermal annealing process, can enhance the crystallization, conductivity, and transmittance of IGZO thin films, which can be well used as front-contact electrodes in thin film silicon solar cells.

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