scholarly journals Assessing Rapid Variability in Atmospheric Apparent Optical Depth with an Array Spectrometer System

2020 ◽  
Vol 12 (18) ◽  
pp. 2917
Author(s):  
Josep-Abel González ◽  
Josep Calbó
Keyword(s):  
Water Vapor ◽  
Optical Depth ◽  
Near Infrared ◽  
Absolute Calibration ◽  
Cloud Droplets ◽  
Rapid Variation ◽  
Rapid Variability ◽  
Infrared Spectral ◽  
Spectrometer System ◽  
Spectral Ranges

A method for determining rapid variations in atmospheric optical depth is proposed. The method is based upon computation of the ratio between close-time spectral measurements of solar direct flux. Use of the ratio avoids the need for absolute calibration of the instruments and minimizes the effects of changes in instrumental conditions (such as temperature or mechanical adjustments) and in air mass. The technique has been applied to some campaigns of measurement for sky conditions ranging from clear skies to scattered-to-broken cloudiness, performed at high frequency (~1Hz) with a system of three array spectrometers, capable of performing very rapid spectral acquisitions, in the 400 to 1700 nm band, thus covering the visible and extending to the near-infrared spectral ranges. Results demonstrate the capacity of this instrumentation and method to detect rapid variation of optical depth, as well as rapid changes in its spectral pattern. The optical depth variability depends on the particular state of the sky and is connected to particle condensation and evaporation processes and to the changes in water vapor content in the transition region between cloud-free and cloudy regions. Thus, the method is suitable for analyzing rapid processes involving particles, either aerosol or cloud droplets, and water vapor, in the cloud boundaries.

scholarly journals Integrated Optical Phased Arrays for Beam Forming and Steering

2021 ◽  
Vol 11 (9) ◽  
pp. 4017
Author(s):  
Yongjun Guo ◽  
Yuhao Guo ◽  
Chunshu Li ◽  
Hao Zhang ◽  
Xiaoyan Zhou ◽  
...  
Keyword(s):  
Near Infrared ◽  
Phased Arrays ◽  
Mechanical Stability ◽  
Building Blocks ◽  
High Yield ◽  
Beam Forming ◽  
Integrated Optical ◽  
Optical Phased Arrays ◽  
Infrared Spectral ◽  
Spectral Ranges

Integrated optical phased arrays can be used for beam shaping and steering with a small footprint, lightweight, high mechanical stability, low price, and high-yield, benefiting from the mature CMOS-compatible fabrication. This paper reviews the development of integrated optical phased arrays in recent years. The principles, building blocks, and configurations of integrated optical phased arrays for beam forming and steering are presented. Various material platforms can be used to build integrated optical phased arrays, e.g., silicon photonics platforms, III/V platforms, and III–V/silicon hybrid platforms. Integrated optical phased arrays can be implemented in the visible, near-infrared, and mid-infrared spectral ranges. The main performance parameters, such as field of view, beamwidth, sidelobe suppression, modulation speed, power consumption, scalability, and so on, are discussed in detail. Some of the typical applications of integrated optical phased arrays, such as free-space communication, light detection and ranging, imaging, and biological sensing, are shown, with future perspectives provided at the end.

scholarly journals Infrared Absolute Calibration. I. Comparison of Sirius with Fainter Calibration Stars

2022 ◽  
Vol 163 (2) ◽  
pp. 45
Author(s):  
G. H. Rieke ◽  
Kate Su ◽  
G. C. Sloan ◽  
E. Schlawin
Keyword(s):  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Absolute Calibration ◽  
Absolute Flux ◽  
James Webb Space Telescope ◽  
Infrared Spectral ◽  
History Of ◽  
Flux Measurements ◽  
Debris Disk

Abstract A challenge in absolute calibration is to relate very bright stars with physical flux measurements to faint ones within range of modern instruments, e.g., those on large ground-based telescopes or the James Webb Space Telescope (JWST). We propose Sirius as the fiducial color standard. It is an A0V star that is slowly rotating and does not have infrared excesses due to either hot dust or a planetary debris disk; it also has a number of accurate (∼1%–2%) absolute flux measurements. We accurately transfer the near-infrared flux from Sirius to BD +60 1753, an unobscured early A-type star (A1V, V ≈ 9.6, E(B – V) ≈ 0.009) that is faint enough to serve as a primary absolute flux calibrator for JWST. Its near-infrared spectral energy distribution and that of Sirius should be virtually identical. We have determined its output relative to that of Sirius in a number of different ways, all of which give consistent results within ∼1%. We also transfer the calibration to GSPC P330-E, a well-calibrated close solar analog (G2V). We have emphasized the 2MASS K S band, since it represents a large number and long history of measurements, but the theoretical spectra (i.e., from CALSPEC) of these stars can be used to extend this result throughout the near- and mid-infrared.

Three-dimensional silicon-based nanostructures in opal matrix: Preparation and properties

2000 ◽  
Vol 638 ◽  
Author(s):  
A.B. Pevtsov ◽  
V.G. Golubev ◽  
V.A. Kosobukin ◽  
D.A. Kurdyukov ◽  
A.V. Medvedev
Keyword(s):  
Near Infrared ◽  
Photonic Band Gap ◽  
Three Dimensional ◽  
Opal Matrix ◽  
Variable Extent ◽  
Infrared Spectral ◽  
Spectral Ranges ◽  
Silicon Based ◽  
Photonic Band ◽  
Matrix Preparation

AbstractThree-dimensional opal-silicon composites with both direct (a variable extent of filling of opal voids with silicon) and inverted structures have been synthesized. A structural analysis of these fabricated systems is performed. Reflectance spectra from the (111) surface of the composites are measured within the spectral range 400-900 nm. Observed spectral features are interpreted as a manifestation of the [111] direction photonic band gap that is tunable in position and width in the visible and near-infrared spectral ranges.

scholarly journals An optical system for remote sensing in the UV, visible, and NIR spectral ranges

2020 ◽  
Vol 44 (2) ◽  
pp. 195-202
Author(s):  
V.M. Vladimirov ◽  
V.A. Yukseev ◽  
E.G. Lapukhin
Keyword(s):  
Remote Sensing ◽  
Optical System ◽  
Near Infrared ◽  
Ultra Violet ◽  
Field Of View ◽  
Structural Elements ◽  
Earth Remote Sensing ◽  
Infrared Spectral ◽  
Uv Visible ◽  
Spectral Ranges

In this work, we propose a high-resolution optical system for Earth remote sensing, operating at 200-3300-nm wavelengths and providing a 4º field of view. Parameters of the system's structural elements are calculated and presented. Dot charts of the spots of confusion for the center, intermediate zones, and the edge of the field are considered. Over most of the operating wavelengths, the optical system is shown to be diffraction-limited, which provides attaining the highest possible spatial resolution. This system is considered as a tool for monitoring of the Earth's surface and collection of information in the ultra-violet, visible and near infrared spectral ranges (200-3300 nanometers).

scholarly journals Tunneling-induced broadband and tunable optical emission from plasmonic nanorod metamaterials

Nanophotonics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 427-434 ◽  
Author(s):  
Alexey V. Krasavin ◽  
Pan Wang ◽  
Mazhar E. Nasir ◽  
Yunlu Jiang ◽  
Anatoly V. Zayats
Keyword(s):  
Near Infrared ◽  
Light Emission ◽  
Electron Tunneling ◽  
Optical Emission ◽  
Light Sources ◽  
Incoherent Light ◽  
Sensing Platforms ◽  
Infrared Spectral ◽  
Efficient Coupling ◽  
Spectral Ranges

AbstractWe demonstrate a metamaterial platform for electrically driven broadband light emission induced by electron tunneling. Both the Fabry-Perot and waveguided modes of the metamaterial slab as well the plasmonic mode of the tunneling gap are identified as contributing to shaping the emission spectrum. This opens up an opportunity to design the spectrum and polarization of the emitted light by tuning the metamaterial modes via the geometric parameters of the nanostructure throughout the visible and near-infrared spectral ranges. The efficient coupling of the tunneling-induced emission to the waveguided modes is beneficial for the development of integrated incoherent light sources, while the outcoupled emission provides a source of free-space radiation. The demonstrated incoherent nanoscale light sources may find applications in the development of integrated opto-electronic circuits, optical sensing platforms, imaging, and metrology.

scholarly journals The Zugspitze radiative closure experiment for quantifying water vapor absorption over the terrestrial and solar infrared – Part 3: Quantification of the mid- and near-infrared water vapor continuum in the 2500 to 7800 cm<sup>−1</sup> spectral range under atmospheric conditions

2016 ◽  
Vol 16 (18) ◽  
pp. 11671-11686 ◽  
Author(s):  
Andreas Reichert ◽  
Ralf Sussmann
Keyword(s):  
Water Vapor ◽  
Spectral Range ◽  
Near Infrared ◽  
Atmospheric Conditions ◽  
Water Vapor Absorption ◽  
Absorption Bands ◽  
Continuum Absorption ◽  
Upper Limits ◽  
Vapor Absorption ◽  
Spectral Ranges

Abstract. We present a first quantification of the near-infrared (NIR) water vapor continuum absorption from an atmospheric radiative closure experiment carried out at the Zugspitze (47.42° N, 10.98° E; 2964 m a.s.l.). Continuum quantification is achieved via radiative closure using radiometrically calibrated solar Fourier transform infrared (FTIR) absorption spectra covering the 2500 to 7800 cm−1 spectral range. The dry atmospheric conditions at the Zugspitze site (IWV 1.4 to 3.3 mm) enable continuum quantification even within water vapor absorption bands, while upper limits for continuum absorption can be provided in the centers of window regions. Throughout 75 % of the 2500 to 7800 cm−1 spectral range, the Zugspitze results agree within our estimated uncertainty with the widely used MT_CKD 2.5.2 model (Mlawer et al., 2012). In the wings of water vapor absorption bands, our measurements indicate about 2–5 times stronger continuum absorption than MT_CKD, namely in the 2800 to 3000 cm−1 and 4100 to 4200 cm−1 spectral ranges. The measurements are consistent with the laboratory measurements of Mondelain et al. (2015), which rely on cavity ring-down spectroscopy (CDRS), and the calorimetric–interferometric measurements of Bicknell et al. (2006). Compared to the recent FTIR laboratory studies of Ptashnik et al. (2012, 2013), our measurements are consistent within the estimated errors throughout most of the spectral range. However, in the wings of water vapor absorption bands our measurements indicate typically 2–3 times weaker continuum absorption under atmospheric conditions, namely in the 3200 to 3400, 4050 to 4200, and 6950 to 7050 cm−1 spectral regions.

Progress Toward Crystalline-Silicon-Based Light-Emitting Diodes

MRS Bulletin ◽  
1993 ◽  
Vol 18 (7) ◽  
pp. 22-28 ◽  
Author(s):  
Leigh Canham
Keyword(s):  
Near Infrared ◽  
Crystalline Silicon ◽  
Light Emitting Diode ◽  
Holy Grail ◽  
Light Emitting ◽  
Vlsi Technology ◽  
Materials Research ◽  
Infrared Spectral ◽  
Spectral Ranges ◽  
Silicon Based

The semiconductor silicon is the dominant material in microelectronics and is one of the best-studied materials known to humanity. Its inability to emit light efficiently is therefore well documented. Nevertheless, a “holy grail” of semiconductor materials research has for decades been the realization of an efficient Si light-emitting diode (LED). Such a device would enable optoelectronic circuitry to be based entirely on silicon and would revolutionize VLSI technology since the other required Si-based devices (detectors, waveguides, modulators, etc.) have already been demonstrated. Although this holy grail has proved elusive, the 1990s have heralded greatly renewed interest and optimism in the development of such devices for both the visible and near-infrared spectral ranges. Dramatic progress is at last being made. This review focuses, in a somewhat chronological manner, on the progress of specific approaches to realizing crystalline structures of high radiative efficiency, and the materials constraints involved.

A Molecular Chameleon: Reversible pH- and Cation-Induced Control of the Optical Properties of Phthalocyanine-Based Complexes in the Visible and Near-Infrared Spectral Ranges

2016 ◽  
Vol 55 (5) ◽  
pp. 2450-2459 ◽  
Author(s):  
Evgeniya A. Safonova ◽  
Alexander G. Martynov ◽  
Sergey E. Nefedov ◽  
Gayane A. Kirakosyan ◽  
Yulia G. Gorbunova ◽  
...  
Keyword(s):  
Optical Properties ◽  
Near Infrared ◽  
Infrared Spectral ◽  
Spectral Ranges

scholarly journals Optical Constants of Chemical Vapor Deposited Graphene for Photonic Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1230
Author(s):  
Marwa A. El-Sayed ◽  
Georgy A. Ermolaev ◽  
Kirill V. Voronin ◽  
Roman I. Romanov ◽  
Gleb I. Tselikov ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Constants ◽  
Near Infrared ◽  
Optoelectronic Devices ◽  
Chemical Vapor ◽  
Multilayer Graphene ◽  
Practical Applications ◽  
Chemical Vapor Deposited ◽  
Infrared Spectral ◽  
Spectral Ranges

Graphene is a promising building block material for developing novel photonic and optoelectronic devices. Here, we report a comprehensive experimental study of chemical-vapor deposited (CVD) monolayer graphene’s optical properties on three different substrates for ultraviolet, visible, and near-infrared spectral ranges (from 240 to 1000 nm). Importantly, our ellipsometric measurements are free from the assumptions of additional nanometer-thick layers of water or other media. This issue is critical for practical applications since otherwise, these additional layers must be included in the design models of various graphene photonic, plasmonic, and optoelectronic devices. We observe a slight difference (not exceeding 5%) in the optical constants of graphene on different substrates. Further, the optical constants reported here are very close to those of graphite, which hints on their applicability to multilayer graphene structures. This work provides reliable data on monolayer graphene’s optical properties, which should be useful for modeling and designing photonic devices with graphene.

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