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James A Harrington - One of the best experts on this subject based on the ideXlab platform.
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theory and practical considerations of multilayer Dielectric Thin film stacks in ag coated hollow waveguides
Applied Optics, 2014Co-Authors: Carlos M Bledt, Jeffrey E Melzer, James A HarringtonAbstract:This analysis explores the theory and design of Dielectric multilayer reflection-enhancing Thin film stacks based on high and low refractive index alternating layers of cadmium sulfide (CdS) and lead sulfide (PbS) on silver (Ag)-coated hollow glass waveguides (HGWs) for low loss transmission at midinfrared wavelengths. The fundamentals for determining propagation losses in such multilayer Thin-film-coated Ag hollow waveguides is thoroughly discussed, and forms the basis for further theoretical analysis presented in this study. The effects on propagation loss resulting from several key parameters of these multilayer Thin film stacks is further explored in order to bridge the gap between results predicted through calculation under ideal conditions and deviations from such ideal models that often arise in practice. In particular, the effects on loss due to the number of Dielectric Thin film layers deposited, deviation from ideal individual layer thicknesses, and surface roughness related scattering losses are presented and thoroughly investigated. Through such extensive theoretical analysis the level of understanding of the underlying loss mechanisms of multilayer Thin-film Ag-coated HGWs is greatly advanced, considerably increasing the potential practical development of next-generation ultralow-loss mid-IR Ag/multilayer Dielectric-coated HGWs.
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investigation of metal sulfide optical Thin film growth in low loss ir hollow glass waveguides
Optical Materials Express, 2013Co-Authors: Carlos M Bledt, Jeffrey E Melzer, James A HarringtonAbstract:In this study, the film growth kinetics for near and mid-IR reflection enhancing CdS and PbS Dielectric Thin films in HGWs is experimentally established. Crucial fabrication parameters including solution concentrations, pH, and fluid velocity are optimized. The film thickness of these films in HGWs is studied as a function of deposition time and temperature. Through IR spectral response analysis, the Dielectric Thin film thicknesses were determined and found to have a strong linear time dependence. Accurate metal sulfide film growth models in HGWs were developed, allowing for direct determination of necessary deposition times to yield metal sulfide HGW Thin film coatings having a desired response.
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deposition and characterization of metal sulfide Dielectric coatings for hollow glass waveguides
Optics Express, 2003Co-Authors: Veena Gopal, James A HarringtonAbstract:Metal sulfide Dielectric Thin films have been deposited using dynamic wet chemistry processing on silver coated hollow glass waveguides (HGWs). The sulfides used were cadmium sulfide (CdS) and lead sulfide (PbS); both films have excellent infrared transparency and high refractive index contrast. The thickness of these Thin films can be tailored to minimize the attenuation of the HGW over specific infrared wavelengths. We have made both single and multiple Dielectric (2 and 3 layer) metal coated HGWs using CdS and PbS deposited over an inner Ag layer. The straight lowest loss measured at 1.55 µm for a 1,000-µm bore Ag/CdS/PbS/CdS HGW was 0.06 dB/m. This loss is three times less than that measured for a single layer Ag/CdS coated HGW at 1.55 µm.
Akhlesh Lakhtakia - One of the best experts on this subject based on the ideXlab platform.
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development and assessment of coupled wave theory of axial propagation in Thin film helicoidal bianisotropic media part 1 reflectances and transmittances
Journal of Modern Optics, 2000Co-Authors: Martin W Mccall, Akhlesh LakhtakiaAbstract:Abstract The coupled wave theory (CWT) for axial propagation of light in Dielectric Thin-film helicoidal bianisotropic media is presented and compared with the full electromagnetic analysis (FEMA). Two sets of formulas are developed for the location and bandwidth of the wavelength regime wherein the circular Bragg phenomenon is exhibited. Multi-layer structures are also analysed using the CWT, the location of the spectral hole in a class of threelayer structures being determined analytically. Absorption and dispersion effects are considered.
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electromagnetic plane wave response characteristics of non axially excited slabs of Dielectric Thin film helicoidal bianisotropic mediums
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2000Co-Authors: Vijayakumar C Venugopal, Akhlesh LakhtakiaAbstract:Thin–film helicoidal bianisotropic mediums (TFHBMs) are rotationally non–homogeneous mediums whose microstructure consists of parallel helical columns. We characterize here the plane–wave response of non–axially excited Dielectric TFHBM slabs. The constitutive relations for the Dielectric TFHBMs are substituted into the time–harmonic Maxwell curl equations, and a 4 × 4 matrix ordinary differential equation is obtained. The piecewise homogeneity approximation method is shown to be reasonably robust to solve the differential equation. Bragg reflection by non–axially excited Dielectric TFHBM slabs is investigated, and transmission characteristics are examined. The effects of several key illumination and constitutive parameters on the response of non–axially excited Dielectric TFHBM slabs are studied to elucidate trends in functional relationships. A TFHBM bilayer is presented as an example of a device based on non–axially excited Dielectric TFHBMs.
Kun Zhou - One of the best experts on this subject based on the ideXlab platform.
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control of nanoplane orientation in vobn for high thermal anisotropy in a Dielectric Thin film a new solution for thermal hotspot mitigation in electronics
ACS Applied Materials & Interfaces, 2017Co-Authors: Olivier Cometto, Majid Kabiri Samani, Siu Hon Tsang, Kun ZhouAbstract:High anisotropic thermal materials, which allow heat to dissipate in a preferential direction, are of interest as a prospective material for electronics as an effective thermal management solution for hot spots. However, due to their preferential heat propagation in the in-plane direction, the heat spreads laterally instead of vertically. This limitation makes these materials ineffective as the density of hot spots increases. Here, we produce a new Dielectric Thin film material at room temperature, named vertically ordered nanocrystalline h-BN (voBN). It is produced such that its preferential thermally conductive direction is aligned in the vertical axis, which facilitates direct thermal extraction, thereby addressing the increasing challenge of thermal crosstalk. The uniqueness of voBN comes from its h-BN nanocrystals where all their basal planes are aligned in the direction normal to the substrate plane. Using the 3ω method, we show that voBN exhibits high anisotropic thermal conductivity (TC) with a 16...
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Control of Nanoplane Orientation in voBN for High Thermal Anisotropy in a Dielectric Thin Film: A New Solution for Thermal Hotspot Mitigation in Electronics
2017Co-Authors: Olivier Cometto, Majid Kabiri Samani, Siu Hon Tsang, Kun Zhou, Bo Liu, Shuangxi Sun, Johan Liu, Edwin H. T. TeoAbstract:High anisotropic thermal materials, which allow heat to dissipate in a preferential direction, are of interest as a prospective material for electronics as an effective thermal management solution for hot spots. However, due to their preferential heat propagation in the in-plane direction, the heat spreads laterally instead of vertically. This limitation makes these materials ineffective as the density of hot spots increases. Here, we produce a new Dielectric Thin film material at room temperature, named vertically ordered nanocrystalline h-BN (voBN). It is produced such that its preferential thermally conductive direction is aligned in the vertical axis, which facilitates direct thermal extraction, thereby addressing the increasing challenge of thermal crosstalk. The uniqueness of voBN comes from its h-BN nanocrystals where all their basal planes are aligned in the direction normal to the substrate plane. Using the 3ω method, we show that voBN exhibits high anisotropic thermal conductivity (TC) with a 16-fold difference between through-film TC and in-plane TC (respectively 4.26 and 0.26 W·m–1·K–1). Molecular dynamics simulations also concurred with the experimental data, showing that the origin of this anisotropic behavior is due to the nature of voBN’s plane ordering. While the consistent vertical ordering provides an uninterrupted and preferred propagation path for phonons in the through-film direction, discontinuity in the lateral direction leads to a reduced in-plane TC. In addition, we also use COMSOL to simulate how the Dielectric and thermal properties of voBN enable an increase in hot spot density up to 295% compared with SiO2, without any temperature increase
S Tougaard - One of the best experts on this subject based on the ideXlab platform.
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Dielectric and optical properties of zr silicate Thin films grown on si 100 by atomic layer deposition
Journal of Applied Physics, 2009Co-Authors: Dahlang Tahir, Eun Kyoung Lee, Hee Jae Kang, Sung Heo, Jae Gwan Chung, Jaecheol Lee, S TougaardAbstract:Dielectric and optical properties of (ZrO2)x(SiO2)1−x Dielectric Thin films, grown on Si(100) by the atomic layer deposition method, were studied by means of reflection electron energy loss spectroscopy (REELS). The quantitative analysis of REELS spectra was carried out by using the quantitative analysis of electron energy loss spectra-e(k,ω)-REELS software to determine the Dielectric function and optical properties by using an analysis of experimental REELS cross sections from the simulated energy loss function (ELF). For ZrO2, the ELF shows peaks in the vicinity of 10, 15, 21, 27, 35, 42, and 57 eV. For SiO2, a broad peak at 23 eV with a very weak shoulder at 15 eV and a shoulder at 34 eV were observed, while for Zr silicates (x=0.75 and 0.5), the peak position is similar to that of ZrO2. For Zr silicates with high SiO2 concentration (x=0.25), the peak positions are similar to that of SiO2, but the peak at 42 eV, which is due to excitation of Zr N2,3 shell electrons, still exist. This indicates that the...
Olivier Cometto - One of the best experts on this subject based on the ideXlab platform.
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control of nanoplane orientation in vobn for high thermal anisotropy in a Dielectric Thin film a new solution for thermal hotspot mitigation in electronics
ACS Applied Materials & Interfaces, 2017Co-Authors: Olivier Cometto, Majid Kabiri Samani, Siu Hon Tsang, Kun ZhouAbstract:High anisotropic thermal materials, which allow heat to dissipate in a preferential direction, are of interest as a prospective material for electronics as an effective thermal management solution for hot spots. However, due to their preferential heat propagation in the in-plane direction, the heat spreads laterally instead of vertically. This limitation makes these materials ineffective as the density of hot spots increases. Here, we produce a new Dielectric Thin film material at room temperature, named vertically ordered nanocrystalline h-BN (voBN). It is produced such that its preferential thermally conductive direction is aligned in the vertical axis, which facilitates direct thermal extraction, thereby addressing the increasing challenge of thermal crosstalk. The uniqueness of voBN comes from its h-BN nanocrystals where all their basal planes are aligned in the direction normal to the substrate plane. Using the 3ω method, we show that voBN exhibits high anisotropic thermal conductivity (TC) with a 16...
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Control of Nanoplane Orientation in voBN for High Thermal Anisotropy in a Dielectric Thin Film: A New Solution for Thermal Hotspot Mitigation in Electronics
2017Co-Authors: Olivier Cometto, Majid Kabiri Samani, Siu Hon Tsang, Kun Zhou, Bo Liu, Shuangxi Sun, Johan Liu, Edwin H. T. TeoAbstract:High anisotropic thermal materials, which allow heat to dissipate in a preferential direction, are of interest as a prospective material for electronics as an effective thermal management solution for hot spots. However, due to their preferential heat propagation in the in-plane direction, the heat spreads laterally instead of vertically. This limitation makes these materials ineffective as the density of hot spots increases. Here, we produce a new Dielectric Thin film material at room temperature, named vertically ordered nanocrystalline h-BN (voBN). It is produced such that its preferential thermally conductive direction is aligned in the vertical axis, which facilitates direct thermal extraction, thereby addressing the increasing challenge of thermal crosstalk. The uniqueness of voBN comes from its h-BN nanocrystals where all their basal planes are aligned in the direction normal to the substrate plane. Using the 3ω method, we show that voBN exhibits high anisotropic thermal conductivity (TC) with a 16-fold difference between through-film TC and in-plane TC (respectively 4.26 and 0.26 W·m–1·K–1). Molecular dynamics simulations also concurred with the experimental data, showing that the origin of this anisotropic behavior is due to the nature of voBN’s plane ordering. While the consistent vertical ordering provides an uninterrupted and preferred propagation path for phonons in the through-film direction, discontinuity in the lateral direction leads to a reduced in-plane TC. In addition, we also use COMSOL to simulate how the Dielectric and thermal properties of voBN enable an increase in hot spot density up to 295% compared with SiO2, without any temperature increase