Enhanced Coherency of Thermal Emission From SiC by Coupled Resonant Cavity Structure

2008 ◽  
Author(s):  
Nir Dahan ◽  
Avi Niv ◽  
Yuri Gorodetski ◽  
Vladimir Kleiner ◽  
Erez Hasman
Keyword(s):  
Surface Waves ◽  
Thermal Emission ◽  
Near Field ◽  
Resonant Cavity ◽  
Spatial Coherence ◽  
Support Surface ◽  
Amorphous Sio2 ◽  
Coherent Coupling ◽  
Cavity Structure ◽  
Order Of Magnitude

Surface waves have been shown to play a key role in spontaneous thermal emission in the near-field as well as the coherence and the polarization properties of the nonradiative field. The near-field coherence of the delocalized nonradiative surface waves can be transferred into radiative fields by introducing a shallow grating on the surface. We show that the coherency of the thermal radiation can be enhanced by an order of magnitude compared with the coherency imposed by the delocalized surface waves. The enhanced coherency is due to coherent coupling between resonant cavities obtained by surface standing waves, where each cavity supports localized field that is attributed to coupled surface waves. We realized coupled resonant cavity structure on amorphous SiO2 and crystalline SiC, both support surface phonon-polaritons, to demonstrate extraordinary coherent thermal emission with a high quality factor of 600 and a spatial coherence length of 760λ.

Coherent Thermal Emission From Modified Periodic Multilayer Structures

2005 ◽  
Author(s):  
B. J. Lee ◽  
Z. M. Zhang
Keyword(s):  
Photonic Crystal ◽  
Surface Waves ◽  
Thermal Emission ◽  
Cavity Resonance ◽  
Support Surface ◽  
Emission Sources ◽  
Surface Polaritons ◽  
Propagating Waves ◽  
Coherent Emission ◽  
And Control

Enhancement of thermal emission and control of its direction are important for applications in optoelectronics and energy conversion. A number of structures have been proposed as coherent emission sources, which exhibit a large emissivity peak within a narrow wavelength band and at well-defined directions. A commonly used structure is gratings, in which the excited surface polaritons or surface waves are coupled with propagating waves in air to produce coherent emission for p polarization. One-dimensional photonic crystals can also support surface waves but have not been applied as coherent emission sources. The present study demonstrates that coherent emission can be achieved by the use of a multilayer structure consisting of periodic layers (i.e., photonic crystal) coated with a polar material such as SiC. By excitation of surface waves at the interface between SiC and the photonic crystal, coherent emission is predicted for both p and s polarization. In addition to the excitation of surface waves, the emission from the proposed structure can be largely enhanced by the cavity resonance mode, which is very similar to that of Fabry-Perot etalon, as well as by the Brewster mode that occurs only for p polarization.

Coherent control of thermal emission from SiC due to coupled resonant cavity structure

2008 ◽  
Author(s):  
Nir Dahan ◽  
Avi Niv ◽  
Gabriel Biener ◽  
Yuri Gorodetski ◽  
Vladimir Kleiner ◽  
...  
Keyword(s):  
Coherent Control ◽  
Thermal Emission ◽  
Resonant Cavity ◽  
Cavity Structure

Coherent Thermal Emission From Modified Periodic Multilayer Structures

2006 ◽  
Vol 129 (1) ◽  
pp. 17-26 ◽  
Author(s):  
B. J. Lee ◽  
Z. M. Zhang
Keyword(s):  
Surface Waves ◽  
Multilayer Structure ◽  
Thermal Emission ◽  
Cavity Resonance ◽  
Support Surface ◽  
Emission Sources ◽  
Surface Polaritons ◽  
Propagating Waves ◽  
Coherent Emission ◽  
And Control

Enhancement of thermal emission and control of its direction are important for applications in optoelectronics and energy conversion. A number of structures have been proposed as coherent emission sources, which exhibit a large emissivity peak within a narrow wavelength band and at a well-defined direction. A commonly used structure is the grating, in which the excited surface polaritons or surface waves are coupled with propagating waves in air, resulting in coherent emission for p polarization only. One-dimensional photonic crystals can also support surface waves and may be modified to construct coherent emission sources. The present study investigates coherent emission from a multilayer structure consisting of a SiC film coated atop a dielectric photonic crystal (PC). By exciting surface waves at the interface between SiC and the PC, coherent emission is predicted for both p and s polarizations. In addition to the excitation of surface waves, the emission from the proposed multilayer structure can be greatly enhanced by the cavity resonance mode and the Brewster mode.

Near-field scanning optical microscopy

1986 ◽  
Vol 44 ◽  
pp. 642-643
Author(s):  
E. Betzig ◽  
A. Harootunian ◽  
M. Isaacson ◽  
A. Lewis
Keyword(s):  
Near Field ◽  
Optical Microscope ◽  
Visible Radiation ◽  
Field Methods ◽  
Optical Elements ◽  
Optical Region ◽  
Order Of Magnitude ◽  
Nondestructive Imaging ◽  
Scanning Optical Microscopy ◽  
Near Field Scanning

In general, conventional methods of optical imaging are limited in spatial resolution by either the wavelength of the radiation used or by the aberrations of the optical elements. This is true whether one uses a scanning probe or a fixed beam method. The reason for the wavelength limit of resolution is due to the far field methods of producing or detecting the radiation. If one resorts to restricting our probes to the near field optical region, then the possibility exists of obtaining spatial resolutions more than an order of magnitude smaller than the optical wavelength of the radiation used. In this paper, we will describe the principles underlying such "near field" imaging and present some preliminary results from a near field scanning optical microscope (NS0M) that uses visible radiation and is capable of resolutions comparable to an SEM. The advantage of such a technique is the possibility of completely nondestructive imaging in air at spatial resolutions of about 50nm.

The sensitization of laser-induced heat of Er3+ doped Y2O3 nanocrystals by codoped with Mn2+

2015 ◽  
Vol 29 (22) ◽  
pp. 1550158
Author(s):  
Yunfeng Bai ◽  
Minjie Luan ◽  
Linjun Li ◽  
Zhelong He ◽  
Dongyu Li
Keyword(s):  
Power Density ◽  
Thermal Emission ◽  
Energy Levels ◽  
Excitation Power ◽  
Threshold Power ◽  
Excitation Power Density ◽  
Ir Laser ◽  
Order Of Magnitude ◽  
Low Threshold ◽  
Density Threshold

Low threshold power density cw laser-induced heat has been observed in [Formula: see text] and [Formula: see text] codoped [Formula: see text] nanocrystals under excitation by a 980 nm IR laser. Codoped [Formula: see text] remarkably reduces the power density threshold of laser-induced heat compared with [Formula: see text] doped [Formula: see text] nanocrystals. When the excitation power density exceed [Formula: see text], [Formula: see text] codoped [Formula: see text] nanocrystals emit strong blackbody radiation. The thermal emission of [Formula: see text] should originate from the multiphonon relaxation between neighboring energy levels. One additional UC-PL enhancement is observed. The UC-PL intensity can be enhanced by an order of magnitude through high temperature calcination caused by light into heat.

scholarly journals Toggling Near‐Field Directionality via Polarization Control of Surface Waves

2021 ◽  
Vol 15 (4) ◽  
pp. 2000388
Author(s):  
Yuhan Zhong ◽  
Xiao Lin ◽  
Jing Jiang ◽  
Yi Yang ◽  
Gui‐Geng Liu ◽  
...  
Keyword(s):  
Surface Waves ◽  
Near Field ◽  
Polarization Control

Heat Transfer Spectroscopy and “Heat Transfer-Distance” Curves

2008 ◽  
Author(s):  
Arvind Narayanaswamy ◽  
Sheng Shen ◽  
Gang Chen
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Atomic Force Microscope ◽  
Near Field ◽  
Surface Force ◽  
Casimir Forces ◽  
Distance Curve ◽  
Transfer Distance ◽  
Atomic Force ◽  
Order Of Magnitude

Thermal radiative transfer between objects as well as near-field forces such as van der Waals or Casimir forces have their origins in the fluctuations of the electrodynamic field. Near-field radiative transfer between two objects can be enhanced by a few order of magnitude compared to the far-field radiative transfer that can be described by Planck’s theory of blackbody radiation and Kirchoff’s laws. Despite this common origin, experimental techniques of measuring near-field forces (using the surface force apparatus and the atomic force microscope) are more sophisticated than techniques of measuring near-field radiative transfer. In this work, we present an ultra-sensitive experimental technique of measuring near-field using a bi-material atomic force microscope cantilever as the thermal sensor. Just as measurements of near-field forces results in a “force distance curve”, measurement of near-field radiative transfer results in a “heat transfer-distance” curve. Results from the measurement of near-field radiative transfer will be presented.

Sorption of radionuclides to a cementitious backfill material under near-field conditions

2012 ◽  
Vol 76 (8) ◽  
pp. 3401-3410 ◽  
Author(s):  
M. Felipe-Sotelo ◽  
J. Hinchliff ◽  
N. Evans ◽  
P. Warwick ◽  
D. Read
Keyword(s):  
Organic Compounds ◽  
Degradation Products ◽  
Cellulose Degradation ◽  
Near Field ◽  
Organic Ligand ◽  
Sorption Isotherms ◽  
Field Conditions ◽  
Sorption Behaviour ◽  
Backfill Material ◽  
Order Of Magnitude

AbstractThe sorption behaviour of I−, Cs+, Ni2+, Eu3+, Th4+ and UO2+2on NRVB (Nirex reference vault backfill) a possible vault backfill, at pH 12.8 was studied. Sorption isotherms generated were compared to results obtained in the presence of cellulose degradation products (CDP). Whereas Cs was not affected by the presence of the organic compounds, a notable reduction in the sorption of Th and Eu to cement was observed. The results also indicated limited removal of Ni from solution (with or without an organic ligand) by sorption, the concentration in solution seemingly being determined solely by solubility processes. In the case of uranium, the presence of CDP increased the sorption to cement by almost one order of magnitude. Further studies into the uptake of CDP by cement are being undertaken to identify the mechanism(s) responsible.

Pseudo-three-timescale approximation of exponentially modulated free-surface waves

2009 ◽  
Vol 625 ◽  
pp. 435-443 ◽  
Author(s):  
MARK A. KELMANSON
Keyword(s):  
Free Surface ◽  
Surface Waves ◽  
Test Problem ◽  
Evolution Equations ◽  
Film Coating ◽  
Rotating Cylinder ◽  
New Method ◽  
Free Surface Waves ◽  
Numerical Integrations ◽  
Order Of Magnitude

A novel pseudo-three-timescale asymptotic procedure is developed and implemented for obtaining accurate approximations to solutions of an evolution equation arising in thin-film free-surface viscous flow. The new procedure, which employs strained fast and slow timescales, requires considerably fewer calculations than its standard three-timescale counterpart employing fast, slow and slower timescales and may readily be applied to other evolution equations of fluid mechanics possessing wave-like solutions exhibiting exponential decay in amplitude and variations in phase over disparate timescales. The new method is validated on the evolution of free-surface waves on a thin, viscous film coating the exterior of a horizontal rotating cylinder and is shown to yield accurate solutions up to non-dimensional times exceeding by an order of magnitude those of previous related studies. Results of the new method applied to this test problem are demonstrated to be in excellent agreement, over large timescales, with those of corroborative spectrally accurate numerical integrations.

scholarly journals 17. Optical investigations of radio sources: Introductory Lecture

1957 ◽  
Vol 4 ◽  
pp. 107-122 ◽  
Author(s):  
R. Minkowski
Keyword(s):  
Thermal Emission ◽  
Optical Emission ◽  
Radio Spectrum ◽  
Visual Object ◽  
Supporting Evidence ◽  
Precise Position ◽  
Rosette Nebula ◽  
Important Argument ◽  
Astronomical Object ◽  
Order Of Magnitude

Loose agreement of a radio position of low accuracy with that of some object listed in the NGC is not sufficient to provide the identification of a radio source. Even satisfactory coincidence of a precise position with that of an astronomical object requires supporting evidence. Agreement of the size of the source with that of the visible object, at least in order of magnitude, is an important argument in favour of an identification; exact agreement of sizes can be expected only where radio and optical emission are physically connected. The radio spectrum, the optical spectrum, and the physical characteristics of the visual object also have to be taken into account. Observations of the radio spectrum should be particularly useful to support the identification of sources with H 11 regions which can be recognized from their thermal emission even if they are obscured and optically inaccessible. If all data are available, satisfactory agreement exists between optical and radio observations. The best example of this kind at the moment is perhaps NGC 2237, the Rosette nebula, reported as a source by Ko and Krauss (1955) [1] and also observed by Mills, Little and Sheridan (1956 [11]; see also paper 18).

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