scholarly journals Surface Plasmons for Probing Optical Data of Multi- Layered Thin Films

2000 ◽  
Vol 5 ◽  
pp. 105
Author(s):  
A. Rais ◽  
A. Sellai
Keyword(s):  
Surface Plasmons ◽  
Optical Constant ◽  
Incident Light ◽  
Air Gap ◽  
Optical Data ◽  
Layered System ◽  
Geometrical Parameters ◽  
Matrix Formalism ◽  
Minimization Method ◽  
Al Oxide

In this paper, we show how optical excitation of surface plasmons (SPs) can be used to obtain optical and geometrical parameters of specific layers in multi-layered thin film systems. The optimum coupling phenomenon between incoming p-polarized light and SPs appears as a minimum in the reflectance that is calculated using a standard matrix formalism. The sensitive dependence of the reflectance minimum on optical and geometrical parameters suggests that they can be determined accurately by fitting the measured attenuated total reflectance (ATR) to the matrix-calculated reflectance using the Simplex minimization method. The procedure is applied to the multi-layered system: Prism / Air gap / Al-oxide / Al / GaAs. At fixed incident light wavelength, the fitting parameters are the Al-oxide optical constant and the thickness of the air gap, Al-oxide and Al layers. Fortran codes are implemented for the reflectance calculations and the fitting procedures. The results show that the theoretical reflectance fits well the measured ATR at 633 nm wavelength. Moreover, the modeled Al-oxide optical constant at this wavelength agrees well with the literature. However, the reflectance fits are less good at 590 nm and 458 nm wavelengths and their modeled Al-oxide optical constants show a dispersion effect in disagreement with the literature. The modeled geometrical parameters are consistent with the nominal values.

Numerical Modeling of Thermogravitational Convection in Air Gap of System of Rear Ventilated Facades

2014 ◽  
Vol 672-674 ◽  
pp. 1903-1908 ◽  
Author(s):  
Mikhail Petrichenko ◽  
Nikolai Vatin ◽  
Darya Nemova ◽  
Nikita Kharkov ◽  
Artem Korsun
Keyword(s):  
Numerical Modeling ◽  
Stream Temperature ◽  
Air Gap ◽  
Geometrical Parameters ◽  
Thermogravitational Convection

Results of numerical modeling of thermogravitational convection are presented in article in an air layer of systems of rear ventilated facades, dependences of velocity of air and stream temperature on geometrical parameters of an air gap are received.

scholarly journals Nonlinear plasmonic metasurfaces assisted laser mode locking

2020 ◽  
Vol 243 ◽  
pp. 14001
Author(s):  
Lei Zhang ◽  
Jiyong Wang ◽  
Aurelien Coillet ◽  
Philippe Grelu ◽  
Benoit Cluzel ◽  
...  
Keyword(s):  
Transfer Functions ◽  
Incident Light ◽  
Mode Locking ◽  
Pulse Generation ◽  
Nonlinear Regime ◽  
Practical Implementation ◽  
Saturable Absorption ◽  
Geometrical Parameters ◽  
Neuromorphic Circuits ◽  
Saturable Absorbers

Plasmonic metasurfaces are artificial 2D layers made of subwavelength elementary cells, which give rise to novel wave properties that do not exist in nature. In the linear regime, their applications have been extensively studied, especially in wavefront manipulation for lensing, holography or polarization control. Interests in metasurfaces operating in nonlinear regime have also increased due to their ability to efficiently convert the fundamental light into harmonic frequencies and multiphoton emissions. Nevertheless, practical applications in the nonlinear regime have been rarely reported. In this study, we report that plasmonic metasurfaces with well-controlled polarimetric nonlinear transfer functions perform as saturable absorbers with modulation performances superior to that of other 2D materials. We employ planar nanotechnologies to fabricate 2D plasmonic metasurfaces with precise size, gap and orientation. We quantify the relationship between saturable absorption and the plasmonic resonances of the unit cell by altering the excitation power of pumping laser, the polarization of incident light and the geometrical parameters of the plasmonic metasurfaces. Finally, we provide a practical implementation by integrating the saturable metasurfaces into a fiber laser cavity and realize a stable self-starting ultrashort laser pulse generation. As such, this work sheds light on ultrathin nonlinear saturable absorbers for applications where nonlinear functions are required, such as in ultrafast laser or neuromorphic circuits.

Effect of Geometrical Parameters on the Performance of Linear Motor for a Stirling Cooler

2017 ◽  
Vol 25 (04) ◽  
pp. 1750031 ◽  
Author(s):  
V. R. Rajesh ◽  
T. K. Biju
Keyword(s):  
Material Selection ◽  
High Reliability ◽  
Outer Core ◽  
Linear Motor ◽  
Air Gap ◽  
Drive System ◽  
Geometrical Parameters ◽  
Space Applications ◽  
Linear Motors ◽  
Axial Forces

Stirling coolers are becoming more popular in the area of remote sensing and space applications because of their inherent characteristics, viz., long life, high reliability, less weight, etc. In order to have a good onboard performance, the selection of the compressor drive system is crucial. The current development is to replace the conventional crank-driven compressor with a linear motor-driven compressor. Linear motors are simple devices in which axial forces are generated by current flowing in a magnetic field. This paper explores the possibility of employing various combinations of components and their materials for the design of linear drive system. The analysis includes material selection, electromagnetic design and comparison of different configurations in order to meet the stringent operating requirements of the cooler. The compactness of the Stirling cooler is influenced by the available permanent magnet dimensions, the coil winding and the shape of the outer core. Various material combinations were simulated and compared before finalizing the motor geometry. The effect of an increase in magnet height on the flux density of the air gap was studied and the magnetic saturation levels of the inner and outer core were analyzed. The influence of radial air gap on the thrust force was compared for the different configurations. The present study helps in choosing a linear motor with appropriate materials and geometry in the development of a Stirling cooler.

Enhancement of diffraction efficiency for optical gratings

2000 ◽  
Vol 78 (5-6) ◽  
pp. 537-542
Author(s):  
G Z Zhang
Keyword(s):  
Light Beam ◽  
Diffraction Efficiency ◽  
Beam Energy ◽  
Incident Light ◽  
Glass Plate ◽  
Air Gap ◽  
Multiple Reflection ◽  
Input Beam ◽  
Incident Light Beam ◽  
Optical Gratings

A method to increase the diffraction efficiency for optical gratings is proposed. Using a simple glass plate sitting parallel to the top of a grating surface, one can form an air gap between the surfaces of the grating and the glass plate to reflect a grazing-incident light beam and make diffraction through multiple reflection of the beam between the grating and glass plate surfaces. As a result, this device can efficiently enhance the grating efficiency by diffracting the input beam energy into various diffraction orders. PACS Nos.: 07.60-j, 42.25Fx, 42.40Lx, 42.79Dj, 42.40Fg

Achieving superresolution in near-field optical data readout systems using surface plasmons

2005 ◽  
Vol 87 (19) ◽  
pp. 191109 ◽  
Author(s):  
Greg Gbur ◽  
Hugo F. Schouten ◽  
Taco D. Visser
Keyword(s):  
Surface Plasmons ◽  
Near Field ◽  
Optical Data

scholarly journals Modeling of Optical Nanoantennas

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Bedir B. Yousif ◽  
Ahmed S. Samra
Keyword(s):  
Data Storage ◽  
Spectral Response ◽  
Near Field ◽  
Approximation Error ◽  
Field Enhancement ◽  
Optical Data Storage ◽  
Optical Data ◽  
Localized Surface Plasmon ◽  
Geometrical Parameters ◽  
Strong Light

The optical properties of plasmonic nanoantennas are investigated in detail using the finite integration technique (FIT). The validity of this technique is verified by comparison to the exact solution generalized Mie method (GMM). The influence of the geometrical parameters (antenna length, gap dimension, and shapes) on the antenna field enhancement and spectral response is discussed. Localized surface plasmon resonances of Au (gold) dimers nanospheres, bowtie, and aperture bowtie nanoantennas are modeled. The enhanced field is equivalent to a strong light spot which can lead to the resolution improvement of the microscopy and optical lithography, thus increasing the optical data storage capacity. Furthermore, the sensitivity of the antennas to index changes of the environment and substrate is investigated in detail for biosensing applications. We confirm that our approach yields an exact correspondence with GMM theory for Au dimers nanospheres at gap dimensions 5 nm and 10 nm but gives an approximation error of less than 1.37% for gap dimensions 1 nm and 2 nm with diameters approaching 80 nm. In addition, the far-field characteristics of the aperture bowtie nanoantenna such as directivity and gain are studied. The promising results of this study may have useful potential applications in near-field sample detection, optical microscopy, and so forth.

Tensors and matrices in optical mineralogy

1987 ◽  
Vol 51 (363) ◽  
pp. 655-663 ◽  
Author(s):  
A. Peckett
Keyword(s):  
Incident Light ◽  
Polarized Light ◽  
Optical Data ◽  
Dielectric Tensor ◽  
Cell Parameters ◽  
Complex Arithmetic ◽  
Matrix Operations ◽  
Mathematical Techniques ◽  
Polarization Of Light ◽  
Opaque Minerals

AbstractA series of matrix operations is described which enables the following optical data to be calculated for plane polarized light perpendicularly incident on a section of a transparent or opaque mineral: 1. vibration directions and refractive indices of anisotropic transparent minerals: 2. reflectivities and the state of polarization of light reflected from anisotropic opaque minerals. The data needed are the dielectric tensor, its orientation with respect to the crystal axes, the unit cell parameters and the direction of the incident light. The mathematical techniques involve the manipulation of matrices, the determination of eigenvalues and eigenvectors and, for opaque minerals, the manipulation of complex numbers. All operations can be carried out with the aid of some of the recent electronic calculators which have built-in matrix algebra procedures and complex arithmetic.

scholarly journals Photochromism in a New Light: Temperature-Dependent in situ Photocrystallography

2014 ◽  
Vol 70 (a1) ◽  
pp. C767-C767
Author(s):  
Jordan Cox ◽  
Ian Walton ◽  
Dinesh Patel ◽  
Mengyang Xu ◽  
Andrea Markelz ◽  
...  
Keyword(s):  
Data Storage ◽  
Computational Models ◽  
Incident Light ◽  
Anomalous Behavior ◽  
Optical Data Storage ◽  
Optical Data ◽  
Temperature Dependent ◽  
Photochromic Molecules ◽  
Potential Applications

Organic photochromic molecules including diarylethenes are of particular interest for their potential applications in fields of high density optical data storage and light-activated switches, among many others. However, one of the limitations in diarylethene-based systems has been the low photoconversion observed in neat single crystals which is often less than 20%. The low conversion is typically believed to be the result of screening effects in which the photoisomerized molecules at the surface absorb incident light preventing full isomerization of the crystal. To assess the effect of screening on a model diarylethene system, photocrystallographic experiments on microcrystals of the compound were performed using synchrotron radiation at the Advanced Photon Source at Argonne National Labs. During the course of the study, we discovered that the photoconversion of the diarylethene crystals exhibits highly unusual temperature dependent behavior which is incongruent with current computational models of diarylethene photochemistry. Herein we report the first temperature-dependent `constant irradiation' in situ photocrystallography experiments performed on a photochromic system. Through the application of this technique, combined with spectroscopic analysis, we demonstrate that the steady-state population arising from the photo-cyclization reaction shows a temperature dependence which has been heretofore unobserved. Possible explanations for this anomalous behavior and its role in the photochemical reactivity of this and other diarylethene systems will be presented.

Sign in / Sign up

Export Citation Format

Share Document