Anisotropic Polarized Emission of a Doped Silicon Lamellar Grating

2006 ◽  
Vol 129 (1) ◽  
pp. 11-16 ◽  
Author(s):  
F. Marquier ◽  
M. Laroche ◽  
R. Carminati ◽  
J.-J. Greffet
Keyword(s):  
Surface Plasmons ◽  
Angular Dependence ◽  
Thermal Emission ◽  
Azimuthal Angle ◽  
Radiative Cooling ◽  
Polarized Emission ◽  
Doped Silicon ◽  
Resonant Emission ◽  
Thermal Sources ◽  
Total Hemispherical Emissivity

Thermal emission of a doped silicon grating has been studied in the plane perpendicular to the grooves. We show how the excitation of surface plasmons produce a resonant emission weakly depending on the polarization and azimuthal angle. We analyze in detail the polarization and angular dependence of the emission out of the plane perpendicular to the grooves. Two kinds of thermal sources, directional and quasi-isotropic, are studied. They have been designed in a previous paper. We also compute the total hemispherical emissivity of these gratings. In addition we show that in applications such as radiative cooling, these sources are less efficient than other structures.

Transport properties of surface plasmons in a nonlinear nanowire coupled to quantum dots with azimuthal angle differences

2018 ◽  
Vol 419 ◽  
pp. 25-29
Author(s):  
Jin-Song Huang ◽  
Jia-Hao Zhang ◽  
Yan Wang ◽  
Zhong-Hui Xu ◽  
You-Wen Huang
Keyword(s):  
Quantum Dots ◽  
Transport Properties ◽  
Surface Plasmons ◽  
Azimuthal Angle

Pattern Center and Distortion Determined from Faint, Diffuse Electron Diffraction Rings from Amorphous Materials

2017 ◽  
Vol 23 (3) ◽  
pp. 647-660 ◽  
Author(s):  
János L. Lábár ◽  
Partha P. Das
Keyword(s):  
Angular Dependence ◽  
Amorphous Materials ◽  
Azimuthal Angle ◽  
Local Maximum ◽  
Least Square ◽  
Experimental Conditions ◽  
Least Square Fitting ◽  
Marquardt Method ◽  
Single Pattern ◽  
Pattern Center

AbstractDiffuse rings from amorphous materials sit on a steep background resulting in a monotonically decreasing intensity over scattering vector length, frequently with no clear local maximum that could be used to determine the center of the ring. The novelty of the method reported here is that it successful processes such weak patterns. It is based on separating the angular dependence of the positions of the maxima on the azimuthal angle in the measured two-dimensional pattern for a manually preselected peak. Both pattern center and elliptical distortion are simultaneously refined from this angular dependence. Both steps are based on nonlinear least square fitting, using the Levenberg–Marquardt method. It can be successfully applied to any amorphous patterns provided they were recorded with experimental conditions that facilitate dividing them into sectors with acceptable statistics. Patterns with the center shifted to the camera corner (recording a quadrant of a ring) can also be reliably evaluated, keeping precalibrated values of the elliptical distortion fixed during the fit. Finally, the limited number of counts in any pattern is overcome by cumulating many patterns (from equivalent areas) into a single pattern. Eliminating false effects is facilitated by masking out unwanted parts of any recorded pattern from processing.

scholarly journals Thermal Emission Shaping and Radiative Cooling with Thermal Wells, Wires and Dots

2015 ◽  
Author(s):  
Svetlana V. Boriskina ◽  
Jonathan K. Tong ◽  
Lee A. Weinstein ◽  
Wei-Chun Hsu ◽  
Yi Huang ◽  
...  
Keyword(s):  
Thermal Emission ◽  
Radiative Cooling

scholarly journals Metamaterial-Based Radiative Cooling: Towards Energy-Free All-Day Cooling

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 89 ◽  
Author(s):  
Byoungsu Ko ◽  
Dasol Lee ◽  
Trevon Badloe ◽  
Junsuk Rho
Keyword(s):  
Near Infrared ◽  
Thermal Emission ◽  
Cooling System ◽  
Radiative Cooling ◽  
Future Perspectives ◽  
Direct Sunlight ◽  
Basic Principles ◽  
Atmospheric Window ◽  
Window Region ◽  
Reduce Energy Consumption

In the light of the ever increasing dangers of global warming, the efforts to reduce energy consumption by radiative cooling techniques have been designed, but are inefficient under strong sunlight during the daytime. With the advent of metamaterials and their selective control over optical properties, radiative cooling under direct sunlight is now possible. The key principles of metamaterial-based radiative cooling are: almost perfect reflection in the visible and near-infrared spectrum (0.3–3 µm) and high thermal emission in the infrared atmospheric window region (8–13 µm). Based on these two basic principles, studies have been conducted using various materials and structures to find the most efficient radiative cooling system. In this review, we analyze the materials and structures being used for radiative cooling, and suggest the future perspectives as a substitute in the current cooling industry.

scholarly journals Polarized emission by aligned grains in the Mie regime: Application to protoplanetary disks observed by ALMA

2020 ◽  
Vol 634 ◽  
pp. L15 ◽  
Author(s):  
V. Guillet ◽  
J. M. Girart ◽  
A. J. Maury ◽  
F. O. Alves
Keyword(s):  
Magnetic Field ◽  
Grain Size ◽  
Thermal Emission ◽  
Protoplanetary Disks ◽  
Polarization Vector ◽  
Size Distributions ◽  
Negative Polarization ◽  
Polarized Emission ◽  
Grain Size Distributions ◽  
The Magnetic Field

Context. The azimuthal polarization patterns observed in some protoplanetary disks by the Atacama Large Millimetre Array (ALMA) at millimeter wavelengths have raised doubts about whether they are truly produced by dust grains that are aligned with the magnetic field lines. These conclusions were based on the calculations of dust polarized emission in the Rayleigh regime, that is, for grain sizes that are much smaller than the wavelength. However, the grain size in such disks is typically estimated to be in the range of 0.1−1 mm from independent observations. Aims. We study the dust polarization properties of aligned grains in emission in the Mie regime, that is, when the mean grain size approaches the wavelength. Methods. By using the T-MATRIX and DustEM codes, we computed the spectral dependence of the polarization fraction in emission for grains in perfect spinning alignment for various grain size distributions. We restricted our study to weakly-elongated oblate and prolate grains of astrosilicate composition that have a mean size ranging from 10 μm to 1 mm. Results. In the submillimeter and millimeter wavelength range, the polarization by B-field aligned grains becomes negative for grains larger than ∼250 μm, meaning that the polarization vector becomes parallel to the B-field. The transition from the positive to the negative polarization occurs at a wavelength of λ ∼ 1 mm. The regime of negative polarization does not exist for grains that are smaller than ∼100 μm. Conclusions. When using realistic grain size distributions for disks with grains up to the submillimeter sizes, the polarization direction of thermal emission by aligned grains is shown to be parallel to the direction of the magnetic field over a significant fraction of the wavelengths typically used to observe young protoplanetary disks. This property may explain the peculiar azimuthal orientation of the polarization vectors in some of the disks observed with ALMA and attest to the conserved ability of dust polarized emission to trace the magnetic field in disks.

scholarly journals Nanoscale Radiative Heat Flow due to Surface Plasmons in Graphene and Doped Silicon

2012 ◽  
Vol 109 (26) ◽  
Author(s):  
P. J. van Zwol ◽  
S. Thiele ◽  
C. Berger ◽  
W. A. de Heer ◽  
J. Chevrier
Keyword(s):  
Heat Flow ◽  
Surface Plasmons ◽  
Radiative Heat ◽  
Doped Silicon

scholarly journals Infrared surface plasmons on heavily doped silicon

2011 ◽  
Vol 110 (12) ◽  
pp. 123105 ◽  
Author(s):  
Monas Shahzad ◽  
Gautam Medhi ◽  
Robert E. Peale ◽  
Walter R. Buchwald ◽  
Justin W. Cleary ◽  
...  
Keyword(s):  
Surface Plasmons ◽  
Doped Silicon ◽  
Heavily Doped

scholarly journals NON-THERMAL EMISSION FROM GALACTIC JETS

2012 ◽  
Vol 08 ◽  
pp. 84-95
Author(s):  
VALENTÍ BOSCH-RAMON
Keyword(s):  
Gamma Ray ◽  
Thermal Emission ◽  
Galactic Nuclei ◽  
High Energy ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Thermal Emitters ◽  
Thermal Sources ◽  
High Energy Emission ◽  
The Universe

Jets are ubiquitous in the Universe. They are collimated outflows whose origin is associated to an accretion disc and a central object, and can be very powerful non-thermal emitters. Jets form in active galactic nuclei, gamma-ray bursts, microquasars, and young stellar objects. Galactic jets emitting non-thermal emission are typically associated to microquasars, although the jets of massive young stellar objects are also non-thermal sources. The production of non-thermal radiation, in particular radio synchrotron emission, is a clear indication that particle acceleration is taking place in the source, which hints to the generation of photons even at high energies. In this work, we will discuss the emitting sites in, or related to, microquasar jets, and briefly comment on the possibility of high-energy emission in jets from young stellar objects.

scholarly journals Maser and thermal methanol emission in the millimeter wave range: new masers at 1.3 mm and 2.8 mm

2002 ◽  
Vol 206 ◽  
pp. 191-194
Author(s):  
Sergei V. Kalenskii ◽  
Vyacheslav I. Slysh ◽  
Irina E. Val'tts
Keyword(s):  
Thermal Emission ◽  
Class Ii ◽  
Kinetic Temperature ◽  
Star Forming ◽  
Star Forming Regions ◽  
Millimeter Wave Range ◽  
Specific Geometry ◽  
Wave Range ◽  
Methanol Masers ◽  
Thermal Sources

Results of a survey of Galactic star-forming regions in the lines of methanol 8−1 − 70E at 229.8 GHz, 3−2 − 4−1E at 230.0 GHz, 00 − 1−1E at 108.9 GHz, and a series of methanol lines J1 − J0E near 165 GHz are presented. Two masers, DR 21 (OH) and DR 21 West, and two maser candidates, L 379 IRS3 and NGC 6334I(N), as well as 16 thermal sources are found at 229.8 GHz. This is the first detection of methanol masers at a wavelength as short as 1 mm. At 108.9 GHz, masers were found towards G345.01 + 1.79 and probably, towards M 8E. Thermal emission is found towards 28 objects. Only thermal emission was found at 165 and 230.0 GHz (20 and 7 sources, respectively). The masers at 229.8 GHz belong to class I, whereas those at 108.9 GHz belong to class II, according to the classification by Menten (1991). The masers in DR 21 (OH) and DR 21 West can be roughly fitted by models with the gas kinetic temperature of the order of 50 K. The detection of the 108.9 GHz masers towards G345.01 + 1.79 and M 8E may indicate on a specific geometry of these objects. The combination of the existence of the class II J0 - J−1E masers towards W 3(OH), G345.01 + 1.79, W 48, and Cep A and our non-detection of the 3−2 − 4−1E and J1 - J0E lines is an evidence that the class II masers in these objects are pumped by the radiation of hot dust rather than by that of UC HII-regions.

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