Thermal Radiative Properties of a Semitransparent Fiber Coated With a Thin Absorbing Film

2006 ◽  
Vol 129 (6) ◽  
pp. 763-767 ◽  
Author(s):  
Weixue Tian ◽  
Wei Huang ◽  
Wilson K. S. Chiu
Keyword(s):  
Thin Film ◽  
Optical Fibers ◽  
Fiber Surface ◽  
Chemical Vapor ◽  
Fused Silica ◽  
Radiative Properties ◽  
Thermal Radiative Properties ◽  
Proposed Model ◽  
Transport Analysis ◽  
Fiber Radius

This study presents the hemispherical model to predict the hemispherical total thermal radiative properties of a fiber coated with a thin film. The fiber is composed of semi-transparent media, such as fused silica. The film is made of strong absorbing media with thickness on the order of tens of nanometers. The film is assumed to be “locally flat” at the point of incidence for radiative transfer analysis because the thickness of the film is much less than the fiber radius. Wave optics is employed to calculate the reflectance and transmittance of the thin film while the ray tracing method is used for radiative transport analysis of the fiber. Effects of film and fiber substrate optical properties, film thickness and temperature on predicted thermal radiative properties are investigated. One of the applications of the proposed model is for studying the chemical vapor deposition of hermetic coatings on optical fibers, in which the thermal radiative properties of the fiber–film system heavily influence the fiber surface temperature and chemical reaction rate.

Experimental and Numerical Modeling Studies of Laser Chemical Vapor Deposition on Moving Optical Fibers

Volume 3 ◽  
2004 ◽  
Author(s):  
Kinghong Kwok ◽  
Wilson K. S. Chiu
Keyword(s):  
Chemical Vapor Deposition ◽  
Optical Fibers ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Fiber Surface ◽  
Chemical Vapor ◽  
Transfer Model ◽  
Laser Chemical Vapor Deposition ◽  
Protective Films ◽  
The Relationship

An atmospheric-pressure laser-induced chemical vapor deposition (CVD) reactor has been developed that is capable of continuously depositing carbon protective films on moving optical fibers from several hydrocarbon precursors. The relationship between operating parameters and the carbon deposition temperature was investigated experimentally and the results indicate that they are highly dependent on the laser power density and the fiber’s drawing velocity. A computational heat transfer model was developed to calculate the fiber surface temperature during deposition and to provide a deeper understanding of the fundamental principles that govern laser heating and the carbon CVD processes. The surface temperatures obtained from experiments are compared with the calculated temperature in order to validate the numerical model.

Thermal Conductivity Measurement of In0.10Ga0.90As0.96N0.04 Thin Film

2017 ◽  
Author(s):  
Antony Jan ◽  
Ramez Cheaito ◽  
Kenneth E. Goodson ◽  
Bruce M. Clemens
Keyword(s):  
Thin Film ◽  
Thermal Conductivity ◽  
Indium Gallium Arsenide ◽  
Optical Fibers ◽  
Conductivity Measurement ◽  
Chemical Vapor ◽  
Mean Free Path ◽  
Thermal Conductivity Measurement ◽  
Optical Fiber Communications ◽  
Fiber Communications

Dilute indium gallium arsenide nitrides (InxGa1-xAs1-yNy) are valuable in photonic applications as long wavelength emitters and for pairing with silica optical fibers for low attenuation optical fiber communications. The reliable operation of these devices is tied to a precise temperature control and the knowledge of the thermal properties of their components. However, the thermal conductivity of bulk or thin film InGaAsN of any composition are, to the best of our knowledge, not available in literature. In response, we use time-domain thermoreflectance (TDTR) to measure the thermal conductivity of a 78 nm In0.10Ga0.90As0.96N0.04 film grown by metalorganic chemical vapor deposition (MOCVD) on GaAs substrate. The thermal conductivity of In0.10Ga0.90As0.96N0.04 is found to be 6 +/− 0.5 Wm−1K−1, a factor of two lower than that of bulk In0.10Ga0.90As. To our knowledge this is the first reported thermal conductivity measurement on InGaAsN. We also present an analytical model for predicting the thermal conductivity of InGaAsN for any composition. Using this model, we find that the reduction in thermal conductivity can be attributed to the scattering of phonons by nitrogen impurities and boundary scattering of long mean free path phonons from the film thickness.

Effect of Thin Films on Radiative Transport in Chemical Vapor Deposition Systems

1999 ◽  
Author(s):  
Sandip Mazumder ◽  
Alfred Kersch
Keyword(s):  
Thin Film ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Wave Theory ◽  
Radiative Properties ◽  
Wafer Surface ◽  
Contributing Factors ◽  
Thermal Chemical Vapor Deposition ◽  
Wafer Substrate

Abstract The thermal behavior of a wafer during a Rapid Thermal Chemical Vapor Deposition (RTCVD) process depends on its spectral radiative properties, along with other factors. One of the major contributing factors is the thin film that is deposited on the wafer substrate. The presence of a thin film (of thickness anywhere above 0.1 nm) can drastically alter the radiative properties of the wafer surface, thereby leading to significantly different wafer temperatures. This article presents a model to simulate thin film effects in RTCVD processes. Radiative transfer is modeled using a Monte-Carlo ray-tracing technique. Radiative properties are calculated using fundamental Electromagnetic Wave Theory. Simulation results match remarkably well with experimental data, demonstrating the importance of thin film effects.

scholarly journals Tailoring Thin-Film/Lacquer Coatings for Space Applications

2000 ◽  
Vol 12 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Wanda C Peters ◽  
George Harris ◽  
Grace Miller ◽  
John Petro
Keyword(s):  
Thin Film ◽  
Thermal Control ◽  
Radiative Properties ◽  
Space Applications ◽  
Solar Absorptance ◽  
Film Coatings ◽  
Thin Film Coatings ◽  
Thermal Radiative Properties ◽  
Wide Range ◽  
Specular Surfaces

Thin-film coatings have the capability of obtaining a wide range of thermal radiative properties, but the development of thin-film coatings can sometimes be difficult and costly when trying to achieve highly specular surfaces. Given any space mission’s thermal control requirements, there is often a need for a variation of solar absorptance (αs), emittance (∊) and/or highly specular surfaces. The utilization of thin-film coatings is one process of choice for meeting challenging thermal control requirements because of its ability to provide a wide variety of αs/∊ ratios. The radiative properties of thin-film coatings can be tailored to meet specific thermal control requirements through the use of different metals and the variation of dielectric layer thickness. Surface coatings can be spectrally selective to enhance radiative coupling and decoupling. The application of lacquer to a surface can also provide suitable specularity for thin-film application without the cost and difficulty associated with polishing.

Thin Film Deposition Processes

MRS Bulletin ◽  
1988 ◽  
Vol 13 (11) ◽  
pp. 18-21 ◽  
Author(s):  
Russell Messier
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Energy Efficiency ◽  
Optical Fibers ◽  
Chemical Vapor ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Hard Coatings ◽  
Antireflection Coatings ◽  
Deposition Processes

Thin film materials pervade our everyday life as transparent conductors in LCD watches and computer displays and in defrosters for automobiles... antireflection coatings for camera lenses… optical fibers for communication … architectural glass coatings for both color and energy efficiency… solar cells… decorative coatings on plastics such as for toys and automobiles parts… a whole host of electronic and optoelectronic devices… hard coatings for cutting tools, drill bits, and bearings … even metallic coatings inside potato chip bags to keep the chips crisp!Without thin films our lifestyles would be drastically different. And this trend toward increased use of thin film technology will only continue.The varied reasons for using thin films and the specific deposition processes for preparing them are often complex; but usually relate to function, cost, beauty, materials and energy efficiency, and performance. In addition to technological applications, scientists are finding thin films to be an invaluable tool for investigating new physical phenomena, even at the quantum level. For instance, two of the most important new materials—high temperature ceramic superconductors and diamond coatings — are currently being made by several thin film deposition processes in order to explore both their scientific and technological potential.Just 25 years ago the variety of deposition processes for preparing thin films was quite limited. Thin film scientists and technologists had at their disposal electrodeposition, elementary chemical vapor deposition, evaporation, and dc sputtering. Commercial equipment for electron-beam evaporation, a mainstay in the optical coatings industry, was just being developed. Most of the deposition processes reviewed in this and next month's MRS BULLETIN were either not commercially available or were not even conceived of then.

Titanosilicate ETS-10 thin film preparation on fused silica optical fibers

2007 ◽  
Vol 101 (1-2) ◽  
pp. 279-287 ◽  
Author(s):  
Zhaoxia Ji ◽  
Juliusz Warzywoda ◽  
Albert Sacco
Keyword(s):  
Thin Film ◽  
Optical Fibers ◽  
Fused Silica ◽  
Thin Film Preparation ◽  
Film Preparation

Heat Transfer Correlations for a CVD Optical Fiber Coating Process

2002 ◽  
Author(s):  
Patricia O. Iwanik ◽  
Wilson K. S. Chiu
Keyword(s):  
Heat Transfer ◽  
Optical Fibers ◽  
Gas Flow ◽  
Temperature Drop ◽  
Chemical Vapor ◽  
Coating Process ◽  
Numerical Heat Transfer ◽  
Fiber Coating ◽  
Flow And Heat Transfer ◽  
Fiber Radius

A numerical heat transfer study of the chemical vapor deposition coating process used in the manufacture of optical fibers is conducted. A finite volume model, developed to study gas flow and heat transfer in the reactor and heat transfer within the fiber itself, is used. A parametric correlation relating percent temperature drop to the Peclet number and dimensionless fiber radius is determined. This correlation is expanded upon to obtain a correlation for the amount of energy loss as the fiber travels through the reactor. These equations are valid for fiber radius values ranging from 62.5 to 200 μm, and for draw rates ranging from 0.25 to 2.0 m/s.

Simplified Route to Multi-Walled Carbon Nanotube Synthesis by Aerosol Assisted Chemical Vapor Deposition

2008 ◽  
Vol 8 (12) ◽  
pp. 6451-6455 ◽  
Author(s):  
W. Antúnez-Flores ◽  
A. M. Valenzuela-Muñiz ◽  
P. Amézaga-Madrid ◽  
G. Alonso-Nuñez ◽  
Y. Verde ◽  
...  
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Precursor Solution ◽  
Fused Silica ◽  
Oxide Thin Film ◽  
Absolute Methanol ◽  
Set Up

Uniform multi-walled carbon nanotubes (MWCNTs) were obtained decomposing toluene inside of fused silica tubing previously covered with Co oxide thin film. The two-step process, ruled successively in the same aerosol assisted chemical vapor deposition (AACVD) set up, constitutes a simplified route to the synthesis of MWCNTs. First, Co oxide thin film was deposited inside of fused silica tubing at 723 K, using a precursor solution of Co acetate in absolute methanol. After Co oxide deposition, the covered tubing was heated up to 1173 K under Ar flow, then a mist of toluene was injected inside the tubing, using also Ar as carrier gas, consequently MWCNTs were obtained in the internal wall of the tubing. The Co oxide film and the MWCNTs were analyzed by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM). Uniform and very long MWCNTs (several tens of μm) with diameters around 20 to 100 nm were observed, with the advantage that the content of Co particles inside the nanotube was very low.

scholarly journals Thermal Radiative Properties of a Thin Film for Solar Thermal Energy Use

2019 ◽  
Vol 2019 (0) ◽  
pp. 0109
Author(s):  
Koji Miyazaki ◽  
Tomohide Yabuki ◽  
Ryosuke Imaizumi ◽  
Tetsuya Miyagoshi
Keyword(s):  
Thin Film ◽  
Thermal Energy ◽  
Energy Use ◽  
Radiative Properties ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Thermal Radiative Properties

Reaction couples of ceramic thin films prepared by CVD

1988 ◽  
Vol 46 ◽  
pp. 798-799
Author(s):  
D.W. Susnitzky ◽  
S.R. Summerfelt ◽  
C.B. Carter
Keyword(s):  
Thin Film ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Solid State Reactions ◽  
Spatial Distributions ◽  
Diffusion Couples ◽  
Kinetics Studies ◽  
Ceramic Thin Films ◽  
Initial Stage

Solid-state reactions have traditionally been studied in the form of diffusion couples. This ‘bulk’ approach has been modified, for the specific case of the reaction between NiO and Al2O3, by growing NiAl2O4 (spinel) from electron-transparent Al2O3 TEM foils which had been exposed to NiO vapor at 1415°C. This latter ‘thin-film’ approach has been used to characterize the initial stage of spinel formation and to produce clean phase boundaries since further TEM preparation is not required after the reaction is completed. The present study demonstrates that chemical-vapor deposition (CVD) can be used to deposit NiO particles, with controlled size and spatial distributions, onto Al2O3 TEM specimens. Chemical reactions do not occur during the deposition process, since CVD is a relatively low-temperature technique, and thus the NiO-Al2O3 interface can be characterized. Moreover, a series of annealing treatments can be performed on the same sample which allows both Ni0-NiAl2O4 and NiAl2O4-Al2O3 interfaces to be characterized and which therefore makes this technique amenable to kinetics studies of thin-film reactions.

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