scholarly journals “In-gap” Spectroscopy: Reflected-Wave Phase and Film Characterization

2018 ◽  
Vol 63 (11) ◽  
pp. 957
Author(s):  
A. V. Turchin
Keyword(s):  
Inverse Problem ◽  
Light Wave ◽  
Single Layer ◽  
Optical Methods ◽  
Linear Matrix ◽  
Physical Parameters ◽  
Reflection Coefficients ◽  
Linear Matrix Equation ◽  
Reflected Light ◽  
Single Layer Film

Optical methods that are used to characterize the state of a surface covered with films are based on the measurement of either the ratio between the complex reflection coefficients for mutually orthogonal light polarizations (ellipsometry) or the magnitudes of reflection coefficients themselves; afterward, the parameters of films such as their number, thicknesses, and transparencies can be determined by the fitting, while solving the corresponding inverse problem. In order to extend the set of quantities that can bemeasured experimentally, a method is proposed that allows the phase of the reflected light wave to be determined, by analyzing the spectral features for light reflected from a plane-parallel gap between the surface of analyzed specimen and the environment. In particular, the spectrum obtained, by using the “moving specimen” procedure, can be transformed into the spectral dependences of the magnitude and phase of the reflection coefficient. As a result, the inverse problem of finding the dielectric permittivity of a single-layer film is reduced to the solution of a linear matrix equation, which makes the proposed method more advantageous in comparison with the ellipsometric one, for which there is no direct relationships between the ellipsometric angles and the physical parameters of the film.

scholarly journals On-demand light wave manipulation enabled by single-layer dielectric metasurfaces

APL Photonics ◽  
2021 ◽  
Vol 6 (8) ◽  
pp. 086106
Author(s):  
Xuyue Guo ◽  
Bingjie Li ◽  
Xinhao Fan ◽  
Jinzhan Zhong ◽  
Shuxia Qi ◽  
...  
Keyword(s):  
Light Wave ◽  
Single Layer ◽  
On Demand

scholarly journals Electrical tuning of the polarization state of light using graphene-integrated anisotropic metasurfaces

2017 ◽  
Vol 375 (2090) ◽  
pp. 20160061 ◽  
Author(s):  
Shourya Dutta-Gupta ◽  
Nima Dabidian ◽  
Iskandar Kholmanov ◽  
Mikhail A. Belkin ◽  
Gennady Shvets
Keyword(s):  
Tilt Angle ◽  
Incident Light ◽  
Polarization State ◽  
Dynamic Control ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Dynamic Polarization ◽  
Reflected Light ◽  
Electro Optic ◽  
The Way

Plasmonic metasurfaces have been employed for moulding the flow of transmitted and reflected light, thereby enabling numerous applications that benefit from their ultra-thin sub-wavelength format. Their appeal is further enhanced by the incorporation of active electro-optic elements, paving the way for dynamic control of light's properties. In this paper, we realize a dynamic polarization state generator using a graphene-integrated anisotropic metasurface (GIAM) that converts the linear polarization of the incident light into an elliptical one. This is accomplished by using an anisotropic metasurface with two principal polarization axes, one of which possesses a Fano-type resonance. A gate-controlled single-layer graphene integrated with the metasurface was employed as an electro-optic element controlling the phase and intensity of light polarized along the resonant axis of the GIAM. When the incident light is polarized at an angle to the resonant axis of the metasurface, the ellipticity of the reflected light can be dynamically controlled by the application of a gate voltage. Thus accomplished dynamic polarization control is experimentally demonstrated and characterized by measuring the Stokes polarization parameters. Large changes of the ellipticity and the tilt angle of the polarization ellipse are observed. Our measurements show that the tilt angle can be changed from positive values through zero to negative values while keeping the ellipticity constant, potentially paving the way to rapid ellipsometry and other characterization techniques requiring fast polarization shifting. This article is part of the themed issue ‘New horizons for nanophotonics’.

Sol-Gel Derived Titaniajormosil Composite Thin Films For Optical Waveguide Applications

1999 ◽  
Vol 576 ◽  
Author(s):  
Wenxiu Que ◽  
Y. Zhou ◽  
Y. L. Lam ◽  
Y. C. Chan ◽  
S. D. Cheng ◽  
...  
Keyword(s):  
Sol Gel ◽  
Single Layer ◽  
Titanium Content ◽  
Gravimetric Analysis ◽  
Force Microscopy ◽  
Free Film ◽  
Free Silica ◽  
Atomic Force ◽  
Bonding Properties ◽  
Single Layer Film

ABSTRACTWe report the preparation of sol-gel waveguide films based on a newly developed recipe to incorporate organic molecules into the inorganic sol-gel glass matrix. The film was derived from a sol that has a higher titanium content in an organically modified silane (ORMOSIL), namely, ÿ-Glycidoxypropyltrimethoxysilane. We have shown that using spin-coating and low temperature baking, a single coating layer can have a thickness of more than 1.5 μm. When such a single layer film is deposited on a microscope glass slide or a piece of silicon with a buffercladding layer, it is able to support the guiding of optical waves. We have characterized the film using scanning electron microscopy, atomic force microscopy, X-ray diffractometry, thermal gravimetric analysis. differential thermal analysis and Fourier transform infrared spectroscopy and have studied the properties of the waveguide film, including the microstructural properties. the chemical bonding properties, and the optical properties. Based on these experimental results, we found that a heat-treatment at a temperature slightly below 200°C is necessary to attain a dense pore-free film. It has also been noted that a purely inorganic and crack-free silica-titania film can be obtained after baking the titania-ORMOSIL composite film at 500°C or higher.

scholarly journals Infrared Spectroscopy of Jupiter and Saturn

2002 ◽  
Vol 12 ◽  
pp. 96-98
Author(s):  
Pierre Drossart
Keyword(s):  
Remote Sensing ◽  
Infrared Spectroscopy ◽  
Thermal Emission ◽  
Temporal Evolution ◽  
Imaging Spectroscopy ◽  
Giant Planets ◽  
Infrared Range ◽  
Physical Parameters ◽  
Temperature Structure ◽  
Reflected Light

AbstractThe spectroscopy of giant planets in the infrared range gives access to a remote sensing of many physical parameters. The composition, pressure/temperature structure, and the cloud structure all contribute to the spectrum, in solar reflected light below 3 micrometer as well as thermal emission above, from atmospheric levels ranging from the mesosphere down to the troposphere. Imaging spectroscopy revealing the variability of the atmosphere gives access to spatial and temporal evolution of these parameters, constraining the meteorological evolution of the planets.

Optimization of space-constrained micro-perforated absorbers by causality criteria

2021 ◽  
Vol 263 (6) ◽  
pp. 275-286
Author(s):  
Teresa Bravo ◽  
Cedric Maury
Keyword(s):  
Absorption Coefficient ◽  
Low Frequency ◽  
Single Layer ◽  
Optimization Procedure ◽  
Separation Distance ◽  
Physical Parameters ◽  
Total Absorption ◽  
Causality Criterion ◽  
Selection Of ◽  
Total Absorption Coefficient

The problem of space-constrained absorbers in the low frequency range constitutes an area of continuous research. Micro-perforated panels are advantageous because they can be tuned by a proper selection of their constitutive physical parameters including the diameter of the perforations and their separation distance, their thickness and the length of the backing cavity. However, such optimal selection is not straightforward, especially when considering multi-layer partitions. Current optimization algorithms are based on the maximization of the total absorption coefficient averaged over a frequency band, that requires a compromise between the bandwidth and the thickness of the control device. In this work, the problem is analysed on the basis of a causality criterion. This principle is generalized from its formulation in the field of electromagnetism to obtain a relation that correlates the thickness-to-bandwidth performance of a micro-perforated absorber to its total absorption coefficient. Using this relation, an optimization procedure is presented for the sequential selection of the optimal physical parameters for single-layer partitions. An excellent agreement has been found between the optimal values obtained by the causality criterion and those achieved by critical coupling conditions.

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