scholarly journals Parametric Studies on ArtificialMorphoButterfly Wing Scales for Optical Device Applications

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Hyun Myung Kim ◽  
Sang Hyeok Kim ◽  
Gil Ju Lee ◽  
Kyujung Kim ◽  
Young Min Song
Keyword(s):  
Gallium Phosphide ◽  
High Sensitivity ◽  
Membrane Thickness ◽  
Light Sources ◽  
Vapor Sensing ◽  
Reflected Light ◽  
Device Applications ◽  
Parametric Studies ◽  
Geometrical Effects ◽  
Rigorous Coupled Wave

We calculated diffraction efficiencies of grating structures inspired byMorphobutterfly wings by using a rigorous coupled-wave analysis method. The geometrical effects, such as grating width, period, thickness, and material index, were investigated in order to obtain better optical performance. Closely packed grating structures with an optimized membrane thickness show vivid reflected colors and provide high sensitivity to surrounding media variations, which is applicable to vapor sensing or healthcare indicators.Morphostructures with high index materials such as zinc sulfide or gallium phosphide generate white color caused by broadband reflection that can be used as reflected light sources for display applications.

Inter-Pulse Spectroscopy Based on Room-Temperature Pulsed Quantum-Cascade Laser for N2O Detection

2011 ◽  
Vol 128-129 ◽  
pp. 607-610
Author(s):  
Min Wang ◽  
Jie Chen ◽  
Niu Liu ◽  
Ya Wang
Keyword(s):  
Absorption Spectrum ◽  
Room Temperature ◽  
Single Point ◽  
High Sensitivity ◽  
Fast Response ◽  
Trace Gas ◽  
High Resolution Spectrum ◽  
Light Sources ◽  
Quantum Cascade ◽  
Pulse Spectroscopy

Mid-infrared lasers are very suitable for high-sensitive trace-gases detection for their wavelengths cover the fundamental absorption lines of most gases. Quantum-cascade (QC) lasers have been demonstrated to be ideal light sources with its special power, tuning and capability of operating in room-temperature. All these merits make it appropriate for the high resolution spectrum analysis. The absorption spectrum monitoring technology based on the QC laser pulsed operating in the room temperature, combining with the strong absorption of the gas molecule in the basic frequency, has become an effective way to monitor the trace gas with the characteristic of high sensitivity, good selectivity and fast response. In this paper, the inter-pulse spectroscopy based on a room-temperature distributed-feedback pulsed QC laser was introduced. Our approach to trace gas monitoring with QC lasers relies on short current pulses which are designed to produce even shorter light pulses. Each pulse corresponds to a single point in a spectrum. The N2O absorption spectrum centered at 2178.2cm-1was also obtained.

Chaos of interband cascade lasers in the mid-infrared regime

2020 ◽  
Author(s):  
Yu Deng ◽  
Zhuo-Fei Fan ◽  
Shiyuan Zhao ◽  
Frédéric Grillot ◽  
Cheng Wang
Keyword(s):  
Semiconductor Lasers ◽  
Near Infrared ◽  
Optical Feedback ◽  
Nonlinear Dynamical Systems ◽  
Initial Conditions ◽  
Electrical Power ◽  
High Sensitivity ◽  
Light Sources ◽  
Mid Infrared ◽  
Operation Conditions

Abstract Chaos in nonlinear dynamical systems is featured with irregular appearance and with high sensitivity to initial conditions. Near-infrared semiconductor lasers subject to optical feedback from an external reflector are popular chaotic light sources, which have enabled multiple applications. Here, we report the fully-developed chaos in a mid-infrared interband cascade laser with external optical feedback. The chaos leads to significant electrical power enhancement over a frequency span of 500 MHz. In addition, the laser also exhibits periodic oscillations or low-frequency fluctuations before producing chaos, depending on the operation conditions. This work paves the way for extending chaos investigations from the near-infrared regime to the mid-infrared regime, which can stimulate potential applications in this spectral range.

scholarly journals EVN and MERLIN observations of an OH maser ring and a starburst continuum in III Zw 35

2002 ◽  
Vol 206 ◽  
pp. 426-429
Author(s):  
Ylva M. Pihlström ◽  
John E. Conway ◽  
Roy S. Booth
Keyword(s):  
High Sensitivity ◽  
Ring Structure ◽  
Line Of Sight ◽  
Diffuse Emission ◽  
Maser Emission ◽  
Physical Conditions ◽  
Vlbi Observations ◽  
Geometrical Effects ◽  
Western Side ◽  
Luminous Infrared Galaxy

We report on high-sensitivity EVN and MERLIN observations of the OH maser emission and continuum in the luminous infrared galaxy III Zw 35. Earlier VLBI observations have shown two compact maser clumps containing 40%–50% of the single-dish flux. In addition to these compact masers, we detect more diffuse maser emission which lies in a clear ring structure of radius r ∼ 22 pc. The ring appears inclined to the line of sight and the compact masers occur at the tangent points. This structure suggests that the compact and diffuse masers appear different because of geometrical effects and not pumping or other physical conditions. Our observations reveal a velocity gradient along the western side of the disc which indicates rotation. The 18 cm continuum radiation is resolved into a few unresolved sources, plus more diffuse emission and is broadly consistent with emission originating in a starburst.

scholarly journals Analysis of ellipsometric parameters in the reflection of circularly polarized light from a thin anisotropic plate

2021 ◽  
Vol 2094 (2) ◽  
pp. 022071
Author(s):  
V V Yatsyshen
Keyword(s):  
Anisotropic Plate ◽  
Plate Boundary ◽  
Polarized Light ◽  
High Sensitivity ◽  
Incident Radiation ◽  
Angle Of Incidence ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Left Handed ◽  
Reflected Light

Abstract The article presents the results of the analysis of the angular spectra of the ellipsometric parameters of the reflected wave when a circularly polarized light wave is incident on an anisotropic plate. The given dependences show a very high sensitivity of the ellipsometric parameters of the reflected light on the angle of incidence and the angle between the optical axis and the normal to the plate boundary. The energy reflection spectra themselves show much less variability when these parameters change. It should be especially emphasized the nature of the change in the ellipsometric angle Δ, which is responsible for the type of elliptical polarization - when Δ> 0, the polarization is left-handed, and when Δ <0, it is right-handed. It is shown that a thin anisotropic plate at certain angles can serve as a polarization converter of the incident radiation. The ellipsometry parameter ρ characterizes the degree of compression of the ellipse - when ρ = 1, the ellipse is transformed into a circle, and the light is circularly polarized in this case. Thus, a thin anisotropic plate can not only convert left-handed polarization to right-handed, but it can also control the very shape of the polarization ellipse. Such a plate can be used in conjunction with a layered medium, for example, a one-dimensional photonic crystal, to control the polarization of the incident circularly polarized light.

Structure and Characteristics of Electrospun ZnO Nanofibers for Gas Sensing

2020 ◽  
Vol 16 (2) ◽  
pp. 187-195
Author(s):  
Tang-Yu Lai ◽  
Te-Hua Fang ◽  
Yu-Jen Hsiao ◽  
En-Yu Kuo
Keyword(s):  
Gas Sensor ◽  
Photoelectron Spectroscopy ◽  
Gas Sensing ◽  
High Sensitivity ◽  
Oxide Semiconductor ◽  
Woven Fabric ◽  
Membrane Thickness ◽  
One Dimensional ◽  
Sensing Mechanism ◽  
Sensing Material

Background:: A sensing material of zinc oxide (ZnO) was investigated for its use in the electrospun nanofibers for gas sensing. The metal oxide semiconductor gas sensor response is caused by the oxygen that undergoes a chemical reaction on the surface of an oxide, resulting in a change in the measured resistance. Objective:: One-dimensional nanofibers gas sensor have high sensitivity and diverse selectivity. Methods:: One-dimensional nanofiber by an electrospinning method was collected and a sensing membrane was formed. In addition, the gas sensing mechanism was discussed and verified by X-ray photoelectron spectroscopy (XPS). Results:: The ZnO nanofiber membrane had an optimum crystalline phase with a lattice spacing of 0.245 nm and a non-woven fabric structure at a calcination temperature of 500°C, whereas the nanofiber diameter and membrane thickness were about 100 nm and 8 μm, respectively. At an operating temperature of 200°C, the sensing material exhibited good recovery and reproducibility in response to Carbon monoxide (CO), and the concentration was also highly discernible. In addition, the reduction in the peak of OIII at 531.5 to 532.5 eV according to the analysis of XPS was consistent with the description of the sensing mechanism. Conclusion:: The gas sensor of ZnO nanofiber membranes has high sensitivity and diverse selectivity, which can be widely applied in potential applications in various sensors and devices.

scholarly journals RefPlanets: Search for reflected light from extrasolar planets with SPHERE/ZIMPOL

2020 ◽  
Vol 634 ◽  
pp. A69 ◽  
Author(s):  
S. Hunziker ◽  
H. M. Schmid ◽  
D. Mouillet ◽  
J. Milli ◽  
A. Zurlo ◽  
...  
Keyword(s):  
Extrasolar Planets ◽  
Direct Detection ◽  
Speckle Noise ◽  
Detection Methods ◽  
Integration Time ◽  
Light Sources ◽  
Post Processing ◽  
Photon Noise ◽  
Reflected Light ◽  
Blind Search

Aims. RefPlanets is a guaranteed time observation programme that uses the Zurich IMaging POLarimeter (ZIMPOL) of Spectro-Polarimetric High-contrast Exoplanet REsearch instrument at the Very Large Telescope to perform a blind search for exoplanets in wavelengths from 600 to 900 nm. The goals of this study are the characterisation of the unprecedented high polarimetic contrast and polarimetric precision capabilities of ZIMPOL for bright targets, the search for polarised reflected light around some of the closest bright stars to the Sun, and potentially the direct detection of an evolved cold exoplanet for the first time. Methods. For our observations of α Cen A and B, Sirius A, Altair, ɛ Eri and τ Ceti we used the polarimetricdifferential imaging (PDI) mode of ZIMPOL which removes the speckle noise down to the photon noise limit for angular separations ≿0.6′′. We describe some of the instrumental effects that dominate the noise for smaller separations and explain how to remove these additional noise effects in post-processing. We then combine PDI with angular differential imaging as a final layer of post-processing to further improve the contrast limits of our data at these separations. Results. For good observing conditions we achieve polarimetric contrast limits of 15.0–16.3 mag at the effective inner working angle of ~0.13′′, 16.3–18.3 mag at 0.5′′, and 18.8–20.4 mag at 1.5′′. The contrast limits closer in (≾0.6′′) display a significant dependence on observing conditions, while in the photon-noise-dominated regime (≿0.6′′) the limits mainly depend on the brightness of the star and the total integration time. We compare our results with contrast limits from other surveys and review the exoplanet detection limits obtained with different detection methods. For all our targets we achieve unprecedented contrast limits. Despite the high polarimetric contrasts we are not able to find any additional companions or extended polarised light sources in the data obtained so far.

scholarly journals Scalable tactile sensor arrays on flexible substrates with high spatiotemporal resolution enabling slip and grip for closed-loop robotics

2020 ◽  
Vol 6 (46) ◽  
pp. eabd7795
Author(s):  
Hongseok Oh ◽  
Gyu-Chul Yi ◽  
Michael Yip ◽  
Shadi A. Dayeh
Keyword(s):  
Large Scale ◽  
Closed Loop ◽  
Sensor Arrays ◽  
High Sensitivity ◽  
Tactile Sensor ◽  
Flexible Substrates ◽  
Spatiotemporal Resolution ◽  
Reliable Performance ◽  
Device Applications ◽  
Flow Detection

We report large-scale and multiplexed tactile sensors with submillimeter-scale shear sensation and autonomous and real-time closed-loop grip adjustment. We leveraged dual-gate piezoelectric zinc oxide (ZnO) thin-film transistors (TFTs) fabricated on flexible substrates to record normal and shear forces with high sensitivity over a broad range of forces. An individual ZnO TFT can intrinsically sense, amplify, and multiplex force signals, allowing ease of scalability for multiplexing from hundreds of elements with 100-μm spatial and sub–10-ms temporal resolutions. Notably, exclusive feedback from the tactile sensor array enabled rapid adjustment of grip force to slip, enabling the direct autonomous robotic tactile perception with a single modality. For biomedical and implantable device applications, pulse sensing and underwater flow detection were demonstrated. This robust technology, with its reproducible and reliable performance, can be immediately translated for use in industrial and surgical robotics, neuroprosthetics, implantables, and beyond.

A viologen-based coordination polymer exhibiting high sensitivity towards various light sources

CrystEngComm ◽  
2017 ◽  
Vol 19 (4) ◽  
pp. 722-726 ◽  
Author(s):  
Wen-Bo Li ◽  
Qing-Xia Yao ◽  
Li Sun ◽  
Xiao-Dong Yang ◽  
Rui-Yun Guo ◽  
...  
Keyword(s):  
Coordination Polymer ◽  
High Sensitivity ◽  
Light Sources

scholarly journals Scanning acoustic microscopy for material evaluation

2020 ◽  
Vol 50 (1) ◽  
Author(s):  
Hyunung Yu
Keyword(s):  
Cross Sections ◽  
High Efficiency ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Reconstruction Algorithm ◽  
Acoustic Microscopy ◽  
Light Sources ◽  
Scanning Acoustic Microscopy ◽  
Nonlinear Properties ◽  
Additional Information

Abstract Scanning acoustic microscopy (SAM) or Acoustic Micro Imaging (AMI) is a powerful, non-destructive technique that can detect hidden defects in elastic and biological samples as well as non-transparent hard materials. By monitoring the internal features of a sample in three-dimensional integration, this technique can efficiently find physical defects such as cracks, voids, and delamination with high sensitivity. In recent years, advanced techniques such as ultrasound impedance microscopy, ultrasound speed microscopy, and scanning acoustic gigahertz microscopy have been developed for applications in industries and in the medical field to provide additional information on the internal stress, viscoelastic, and anisotropic, or nonlinear properties. X-ray, magnetic resonance, and infrared techniques are the other competitive and widely used methods. However, they have their own advantages and limitations owing to their inherent properties such as different light sources and sensors. This paper provides an overview of the principle of SAM and presents a few results to demonstrate the applications of modern acoustic imaging technology. A variety of inspection modes, such as vertical, horizontal, and diagonal cross-sections have been presented by employing the focus pathway and image reconstruction algorithm. Images have been reconstructed from the reflected echoes resulting from the change in the acoustic impedance at the interface of the material layers or defects. The results described in this paper indicate that the novel acoustic technology can expand the scope of SAM as a versatile diagnostic tool requiring less time and having a high efficiency.

scholarly journals Nonlinear Optics in Silicon Wire Waveguides: Towards Integrated Long Wavelength Light Sources

2012 ◽  
Vol 1437 ◽  
Author(s):  
Bart Kuyken ◽  
Xiaoping Liu ◽  
Richard M. Osgood ◽  
Roel Baets ◽  
Gunther Roelkens ◽  
...  
Keyword(s):  
Nonlinear Optics ◽  
Silicon Nanowire ◽  
Wavelength Region ◽  
High Sensitivity ◽  
Silicon On Insulator ◽  
Light Sources ◽  
Absorption Bands ◽  
Central Wavelength ◽  
Mid Infrared ◽  
Long Wavelength

ABSTRACTMost of the research on silicon-on-insulator integrated circuits has been focused on applications for telecommunication. By using the large refractive index of silicon, compact complex photonic functions have been integrated on a silicon chip. However, the transparency of silicon up to 8.5 μm enables the use of the platform for the mid infrared wavelength region, albeit limited by the absorption in silicon oxide from 4 μm on. This could lead to a whole new set of integrated photonics circuits for sensing, given the distinct absorption bands of many molecules in this wavelength region. These long wavelength integrated photonic circuits would preferably need broadband or widely tunable sources to probe these absorption bands.We propose the use of nonlinear optics in silicon wire waveguides to generate light in this wavelength range. Nonlinear interactions in just a few cm of silicon wire waveguides can be very efficient as a result of both the high nonlinear index of silicon and the high optical confinement obtained in these waveguides. We demonstrate the generation of a supercontinuum spanning from 1.53 μm up to 2.55 μm in a 2 cm dispersion engineered silicon nanowire waveguide by pumping the waveguide with strong picoseconds pulses at 2.12 μm [1]. Furthermore we demonstrate broadband nonlinear optical amplification in the mid infrared up to 50 dB [2] in these silicon waveguides. By using this broadband parametric gain a silicon-based synchronously pumped optical parametric oscillator (OPO) is constructed [3]. This OPO is tunable over 70 nm around a central wavelength of 2080 nm.Finally, we also demonstrate the use of higher order dispersion terms to get phase matching between optical signals at very different optical frequencies in silicon wire waveguides. In this way we demonstrate conversion of signals at 2.44 μm to the telecommunication band with efficiencies up to +19.5 dB [4]. One particularly attractive application of such wide conversion is the possibility of converting weak signals in the mid-IR to the telecom window after which they can be detected by a high-sensitivity telecom-band optical receiver.

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