A Hybrid Partial Coherence and Geometry Optics Model of Radiative Property on Coated Rough Surfaces

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Jun Qiu ◽  
Yuan Ting Wu ◽  
Zhifeng Huang ◽  
Pei-Feng Hsu ◽  
Lin-Hua Liu ◽  
...  
Keyword(s):  
Coating Thickness ◽  
Rough Surfaces ◽  
Scattered Light ◽  
Incident Light ◽  
Fdtd Method ◽  
Partial Coherence ◽  
Radiative Properties ◽  
Wave Number ◽  
Heating Process ◽  
Coherence Effect

Thermal and optical engineering applications of electromagnetic wave scattering from rough surfaces include temperature measurement, radiation heating process, etc. Most of the surfaces have random roughness and are often with coating material different from the substrate. However, the understanding of radiative properties of coated rough surfaces is not well addressed at this point. This paper presented a novel hybrid partial coherence and geometry optics (HPCGO) model to improve the generic geometry optics (GO) prediction by incorporating a previously developed partial coherence reflectance equation. In this way, HPCGO expands the applicable region of GO model and largely reduces the computation time of integrating different wavelength results in the regular hybrid model that considers coherence effect only. In this study, the HPCGO model is first compared with the more rigorous Maxwell equations solvers, the finite-difference time-domain (FDTD) method, and integral equation (IE) method. Then, the HPCGO model is applied to study the coherent effect of directional-hemispherical reflectance from coated rough surfaces. It is found the roughness of coated rough surface can cause partially coherent or noncoherent scattered light even if the incident light source is coherent. It also shows the reflected electromagnetic wave's coherence effect reduces with increased coating thickness and surface roughness, besides the previously recognized incident wave-number bandwidth. The effect of reduce coherence in scattered wave is quantified. Finally a regime map, even limited in the roughness and coating thickness dimensionless parameter ranges, provides the region of validity of the HPCGO model.

A Hybrid Partial Coherence and Geometry Optics Model of Thin Film Optics on Coated Rough Surfaces

2012 ◽  
Author(s):  
Yuan Ting Wu ◽  
Zhi-feng Huang ◽  
Pei-feng Hsu ◽  
Huaichun Zhou
Keyword(s):  
Rough Surfaces ◽  
Scattered Light ◽  
Incident Light ◽  
Fdtd Method ◽  
Computation Time ◽  
Partial Coherence ◽  
Wave Number ◽  
Heating Process ◽  
Coherent Effect ◽  
Coherence Effect

Thermal and optical engineering applications of electromagnetic wave reflectance from rough surfaces include temperature measurement, radiation heating process, etc. Most of the surfaces are random roughness and often with coating material different from the substrate. This paper presented a novel hybrid partial coherence and geometry optics (HPCGO) model to improve the generic geometry optics (GO) method by incorporating a previously developed partial coherence reflectance equation. In this way, HPCGO expands the applicable region of GO model, and largely reduces the computation time of integrating different wavelength results in the regular hybrid model that considers coherence effect only. First, the HPCGO model is validated by more rigorous Maxwell equations solvers, for example, the finite-difference time-domain (FDTD) method and integral equation (IE) method. Then, the HPCGO model is applied to study the coherent effect of directional-hemispherical reflectance from coated rough surfaces. It is found the roughness of coated rough surface can cause partial or non-coherent scattered light even if the incident light source is coherent. It also shows the coherence effect reduces with increased incident wave-number bandwidth.

scholarly journals Stimulated Raman scattering in a non-eigenmode regime

2020 ◽  
Vol 8 ◽  
Author(s):  
Yao Zhao ◽  
Suming Weng ◽  
Zhengming Sheng ◽  
Jianqiang Zhu
Keyword(s):  
Raman Scattering ◽  
Stimulated Raman Scattering ◽  
Laser Energy ◽  
Scattered Light ◽  
Incident Light ◽  
Loss Mechanism ◽  
Constant Frequency ◽  
Electrostatic Wave ◽  
Particle In Cell ◽  
Stimulated Raman

Stimulated Raman scattering (SRS) in plasma in a non-eigenmode regime is studied theoretically and numerically. Different from normal SRS with the eigen electrostatic mode excited, the non-eigenmode SRS is developed at plasma density $n_{e}>0.25n_{c}$ when the laser amplitude is larger than a certain threshold. To satisfy the phase-matching conditions of frequency and wavenumber, the excited electrostatic mode has a constant frequency around half of the incident light frequency $\unicode[STIX]{x1D714}_{0}/2$ , which is no longer the eigenmode of electron plasma wave $\unicode[STIX]{x1D714}_{pe}$ . Both the scattered light and the electrostatic wave are trapped in plasma with their group velocities being zero. Super-hot electrons are produced by the non-eigen electrostatic wave. Our theoretical model is validated by particle-in-cell simulations. The SRS driven in this non-eigenmode regime is an important laser energy loss mechanism in the laser plasma interactions as long as the laser intensity is higher than $10^{15}~\text{W}/\text{cm}^{2}$ .

Distribution of Electromagnetic Field and Energy Flux in the Thin Film Solar Cell with Silver Nano-Disk Array

2013 ◽  
Vol 669 ◽  
pp. 194-203
Author(s):  
Hong Zhou ◽  
Xiao Ping Huang ◽  
Lei Zhong ◽  
Sheng Kang Ji ◽  
Yan Pang ◽  
...  
Keyword(s):  
Thin Film ◽  
Electromagnetic Field ◽  
Solar Cell ◽  
Field Distribution ◽  
Energy Flux ◽  
Thin Film Solar Cell ◽  
Incident Light ◽  
Fdtd Method ◽  
Absorption Enhancement ◽  
Electromagnetic Field Distribution

We simulate and calculate numerically the electromagnetic field and energy flux in single crystal silicon thin film solar cell coated with silver nano-disk square array by using the finite-difference time-domain (FDTD) method. Because of the surface plasmon resonance (SPR) of silver nano array, the electromagnetic field is redistributed and enhanced in the solar cell. The simulation results show that the electromagnetic field distribution and corresponding energy flux component depend on the nano array and the structure of absorbed layer in solar cell. The wavelength of the incident light relative to the nano array determine the profile of the electric field around the nano array. The electromagnetic field distribution in thin film is determined by the internal structure of solar cell. For different incident wavelengths, the electromagnetic field distribution in solar cell will changes. The energy flux named as Poynting vector also changes with the incident wavelength. To investigate the absorption of the solar cell, the normalized absorbed power at different wavelengths is calculated. Based on the SPR effect, the solar cell exhibts absorption enhancement sharply at a certain wavelength.

LIGHT SCATTERING TECHNIQUES FOR DISCRIMINATING BETWEEN OIL AND PARTICULATES IN CONTAMINATED WATER

1977 ◽  
Vol 1977 (1) ◽  
pp. 153-156 ◽  
Author(s):  
Bruce Friedman
Keyword(s):  
Particulate Matter ◽  
Light Scattering ◽  
Intensity Distribution ◽  
Scattered Light ◽  
Incident Light ◽  
Real Life ◽  
The State ◽  
Oil Droplets ◽  
State Of Polarization

ABSTRACT Light scattering techniques are used in several oil-in-water monitors, proposed or in existence. Particulate matter which may interfere with these monitors is also frequently found in oily wastes. An analysis is made of the potential of using measurements of the angular intensity distribution of scattered light in conjunction with determination of the state of polarization of the scattered light for discriminating between oil and particulates. The size conditions which apply to the oil droplets and particulates relative to the incident light allow the scattered light angular intensity distribution to be treated as a consequence of a combination of classical diffraction and of geometrical refraction and reflection. The state of polarization of the scattered light for oil droplets is investigated using expressions for the electric field which are approximations to the expressions of the Mie theory. For the particulate matter, the state of polarization is probed on the basis of light reflected from a plane. It is found that it would be difficult to discriminate between oil and particulates using measurements of the angular intensity distribution of scattered light even in conjunction with the determination of the state of polarization of the scattered light in a real life situation.

scholarly journals The light scattered by gases: its polarisation and intensity

1918 ◽  
Vol 95 (667) ◽  
pp. 155-176 ◽  
Keyword(s):  
Scattered Light ◽  
Incident Light ◽  
Direct Sunlight ◽  
Laboratory Methods

The present investigation is a development in various directions of that described in ‘Proc. Roy. Soc.,’ A, vol. 94, p. 453 (1918). It is there shown that the light scattered by air and other gases in the direction perpendicular to the beam is almost completely polarised. It is of importance to determine whether or not the polarisation of the scattered light at right angles to the beam is absolutely complete. Sky light is by no means completely polarised, but in that case the incident light is not all in one direction: for, besides direct sunlight, light from other parts of the sky and from the earth’s surface contributes to the scattering from any given element of volume. The question is whether, apart from these complications, the polarisation would be complete. This cannot be decided by observations on the sky, but the laboratory methods now described allow of its investigation, not only in air, but in other gases also.

Directional hemispherical radiative properties of random dielectric rough surfaces

2005 ◽  
Vol 15 (4) ◽  
pp. 469-486 ◽  
Author(s):  
F. Ghmari ◽  
I. Sassi ◽  
M. S. Sifaoui
Keyword(s):  
Rough Surfaces ◽  
Radiative Properties

scholarly journals Ultra-Low-Reflective, Self-Cleaning Surface by Fabrication Dual-Scale Hierarchical Optical Structures on Silicon

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1541
Author(s):  
Miaomiao Duan ◽  
Jingjun Wu ◽  
Yubin Zhang ◽  
Ning Zhang ◽  
Jun Chen ◽  
...  
Keyword(s):  
Incident Light ◽  
Fdtd Method ◽  
Silicon Substrates ◽  
Light Emitting ◽  
Reflective Surface ◽  
Silicon Devices ◽  
Scale Structures ◽  
Self Cleaning ◽  
Difference Time ◽  
Dual Scale

An integrated functional anti-reflective surface is of great significance for optical and optoelectronic devices. Hence, its preparation has attracted great attention from many researchers. This study combined wet alkaline etching approaches and reactive ion etching (RIE) techniques to create a dual-scale hierarchical anti-reflective surface on silicon substrates. The effect of RIE time on surface morphology and optical performance was investigated using multiple characterization forms. The optimal parameters for the fabrication of dual-scale structures by the composite etching process were explored. The silicon surface with a dual-scale structure indicated excellent anti-reflective properties (minimum reflectivity of 0.9%) in the 300 to 1100 nm wavelength range. In addition, the ultra-low reflection characteristic of the surface remained prominent at incident light angles up to 60°. The simulated spectra using the finite difference time domain (FDTD) method agreed with the experimental results. Superhydrophobicity and self-cleaning were also attractive properties of the surface. The functionally integrated surface enables silicon devices to have broad application prospects in solar cells, light emitting diodes (LEDs), photoelectric detectors, and outdoor equipment.

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