Analyses of structural films using effective refractive index model

2007 ◽  
Author(s):  
Te-Hung Chang ◽  
Yu-Wen Yeh ◽  
Sheng-Hui Chen ◽  
Cheng-Chung Lee
Keyword(s):  
Refractive Index ◽  
Effective Refractive Index ◽  
Index Model

scholarly journals Optimising the Complex Refractive Index Model for Estimating the Permittivity of Heterogeneous Concrete Models

2021 ◽  
Vol 13 (4) ◽  
pp. 723
Author(s):  
Hossain Zadhoush ◽  
Antonios Giannopoulos ◽  
Iraklis Giannakis
Keyword(s):  
Refractive Index ◽  
Shape Factor ◽  
Complex Refractive Index ◽  
Fdtd Method ◽  
Air Voids ◽  
Water Fraction ◽  
Index Model ◽  
General Complex ◽  
Ground Penetrating ◽  
Fine Tune

Estimating the permittivity of heterogeneous mixtures based on the permittivity of their components is of high importance with many applications in ground penetrating radar (GPR) and in electrodynamics-based sensing in general. Complex Refractive Index Model (CRIM) is the most mainstream approach for estimating the bulk permittivity of heterogeneous materials and has been widely applied for GPR applications. The popularity of CRIM is primarily based on its simplicity while its accuracy has never been rigorously tested. In the current study, an optimised shape factor is derived that is fine-tuned for modelling the dielectric properties of concrete. The bulk permittivity of concrete is expressed with respect to its components i.e., aggregate particles, cement particles, air-voids and volumetric water fraction. Different combinations of the above materials are accurately modelled using the Finite-Difference Time-Domain (FDTD) method. The numerically estimated bulk permittivity is then used to fine-tune the shape factor of the CRIM model. Then, using laboratory measurements it is shown that the revised CRIM model over-performs the default shape factor and provides with more accurate estimations of the bulk permittivity of concrete.

scholarly journals NONLINEAR OPTICAL WAVEGUIDE STRUCTURE FOR SENSOR APPLICATION: TM CASE

2007 ◽  
Vol 21 (30) ◽  
pp. 5075-5089 ◽  
Author(s):  
HALA M. KHALIL ◽  
MOHAMMED M. SHABAT ◽  
SOFYAN A. TAYA ◽  
MAZEN M. ABADLA
Keyword(s):  
Refractive Index ◽  
Theoretical Analysis ◽  
Closed Form ◽  
Optical Waveguide ◽  
Effective Refractive Index ◽  
Nonlinear Optical ◽  
Waveguide Structure ◽  
Analytical Expressions ◽  
Evanescent Waveguide ◽  
Waveguide Sensor

In this work, we present an extensive theoretical analysis of nonlinear optical waveguide sensor. The waveguide under consideration consists of a thin dielectrica film surrounded by a self-focused nonlinear cladding and a linear substrate. The nonlinearity of the cladding is considered to be of Kerr-type. Both cases, when the effective refractive index is greater and when it is smaller than the index of the guiding layer, are discussed. The sensitivity of the effective refractive index to any change in the cladding index in evanescent optical waveguide sensor is derived for TM modes. Closed form analytical expressions and normalized charts are given to provide the conditions required for the sensor to exhibit its maximum sensitivity. The results are compared with those of the well-known linear evanescent waveguide sensors.

scholarly journals Titania Photonic Crystals with Precise Photonic Band Gap Position via Anodizing with Voltage versus Optical Path Length Modulation

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 651 ◽  
Author(s):  
Ermolaev ◽  
Kushnir ◽  
Sapoletova ◽  
Napolskii
Keyword(s):  
Refractive Index ◽  
Photonic Crystals ◽  
Band Gap ◽  
Titanium Oxide ◽  
Effective Refractive Index ◽  
Photonic Band Gap ◽  
Voltage Versus ◽  
Research Attention ◽  
Anodic Titanium Oxide ◽  
Photonic Band

Photonic crystals based on titanium oxide are promising for optoelectronic applications, for example as components of solar cells and photodetectors. These materials attract great research attention because of the high refractive index of TiO2. One of the promising routes to prepare photonic crystals based on titanium oxide is titanium anodizing at periodically changing voltage or current. However, precise control of the photonic band gap position in anodic titania films is a challenge. To solve this problem, systematic data on the effective refractive index of the porous anodic titanium oxide are required. In this research, we determine quantitatively the dependence of the effective refractive index of porous anodic titanium oxide on the anodizing regime and develop a model which allows one to predict and, therefore, control photonic band gap position in the visible spectrum range with an accuracy better than 98.5%. The prospects of anodic titania photonic crystals implementation as refractive index sensors are demonstrated.

scholarly journals Optimal ash particle refractive index model for simulating the brightness temperature spectrum of volcanic ash clouds from satellite infrared sounder measurements

2021 ◽  
Author(s):  
Hiroshi Ishimoto ◽  
Masahiro Hayashi ◽  
Yuzo Mano
Keyword(s):  
Refractive Index ◽  
Brightness Temperature ◽  
Volcanic Ash ◽  
Satellite Measurements ◽  
Temperature Spectrum ◽  
Index Model ◽  
Rock Types ◽  
Volcanic Events ◽  
Atmospheric Sounding ◽  
Using Data

Abstract. Using data from the Infrared Atmospheric Sounding Interferometer (IASI) measurements of volcanic ash clouds and radiative transfer calculations, we identify the optimal refractive index model for simulating the measured brightness temperature spectrum of volcanic ash material. We assume that the optimal refractive index model has the smallest root mean square of the brightness temperature difference between measurements and simulations for channels in the wavenumber range of 750–1400 cm−1 and compare 21 refractive index models for optical properties of ash particles, including recently published models. From the results of numerical simulations for 164 pixels of IASI measurements for ash clouds from 11 volcanoes, we found that the measured brightness temperature spectrum could be well simulated using certain newly established refractive index models. In the cases of Eyjafjallajökull and Grímsvötn ash clouds, the optimal refractive index models determined through numerical simulation correspond to those deduced from the chemical composition of ash samples for the same volcanic eruption events. This finding suggests that infrared sounder measurement of volcanic ash clouds is an effective approach to estimating the optimal refractive index model. However, discrepancies between the estimated refractive index models based on satellite measurements and the associated volcanic rock types were observed for some volcanic events.

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