scholarly journals Development of a high frequency ultrasonic setup for measuring the parameters of thin films

2021 ◽  
Vol 2127 (1) ◽  
pp. 012057
Author(s):  
P S Martyanov ◽  
P V Zinin ◽  
S A Titov
Keyword(s):  
Acoustic Waves ◽  
Strain Field ◽  
Laser Pulse Energy ◽  
Ultrasonic Waves ◽  
Nanosecond Laser ◽  
Incident Laser ◽  
Incident Laser Pulse ◽  
Elastic Process ◽  
Subsurface Material ◽  
Novel Method

Abstract In this report a novel method for measuring the elastic properties of thin 10 nm films is described. The method is based on the use of a nanosecond laser for generation acoustic waves in solids. Absorption of the incident laser pulse energy and the associated temperature gradients induces a rapidly changing strain field. This strain field, in turn, radiates energy as elastic (ultrasonic) waves. At low pulse power, this is an entirely thermo elastic process resulting in no damage to the sample. The acoustic echo arriving at the probed surface causes both the displacement of the surface (a few nanometres) and the strain in the subsurface material, which might be detected through the variation of the optical reflectivity of the material, i.e. through the acousto-optic effect.

Simulation of the Transient Behavior of Matter with Characteristic Geometrical Variations & Defects Irradiated by Nanosecond Laser Pulses Using FEA

2015 ◽  
Vol 665 ◽  
pp. 157-160
Author(s):  
Evaggelos Kaselouris ◽  
Emmanouil Skarvelakis ◽  
Ioannis K. Nikolos ◽  
Georgios E. Stavroulakis ◽  
Yannis Orphanos ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Three Dimensional ◽  
Transient Behavior ◽  
Laser Pulses ◽  
Ultrasonic Waves ◽  
Nanosecond Laser ◽  
Element Analysis ◽  
Fea Model ◽  
Nanosecond Laser Pulses ◽  
The Impact

The thermomechanical transient response of matter illuminated by nanosecond laser pulses is modeled and simulated using the Finite Element Analysis (FEA). Matter’s behavior is numerically described by a three-dimensional (3D) multiphysics, coupled thermal structural, transient FEA, experimentally validated, model. FEA offers substantial insights into the materials’ micro-mechanical behaviour providing detailed information for the spatiotemporal evolution of acoustic waves. In this computational approach the impact of the geometric characteristics of the modeled metallic films to the generation and propagation of the ultrasonic waves, in relation to temperature, is investigated. The study is expanded to the dynamic reactions of matter in the presence of surface and solid volume defects and enclosures e.g.: gaps, holes or bubbles. The transient behavior of matter in the time and the space solution domains is obtained by the FEA model and presented.

Influence of the incident laser pulse energy on jitter time of GaAs photoconductive semiconductor switches

2013 ◽  
Vol 38 (21) ◽  
pp. 4339 ◽  
Author(s):  
Wei Shi ◽  
Huai-meng Gui ◽  
Lin Zhang ◽  
Meng-xia Li ◽  
Cheng Ma ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Pulse Energy ◽  
Laser Pulse Energy ◽  
Incident Laser ◽  
Semiconductor Switches ◽  
Incident Laser Pulse

scholarly journals Ultrasonic Waves in Bubbly Liquids: An Analytic Approach

Mathematics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1309
Author(s):  
P. R. Gordoa ◽  
A. Pickering
Keyword(s):  
Mathematical Model ◽  
Partial Differential Equations ◽  
Differential Equations ◽  
Acoustic Waves ◽  
Elliptic Functions ◽  
Coupled System ◽  
Ultrasonic Waves ◽  
Partial Differential ◽  
Special Cases ◽  
Spherical Bubbles

We consider the problem of the propagation of high-intensity acoustic waves in a bubble layer consisting of spherical bubbles of identical size with a uniform distribution. The mathematical model is a coupled system of partial differential equations for the acoustic pressure and the instantaneous radius of the bubbles consisting of the wave equation coupled with the Rayleigh–Plesset equation. We perform an analytic analysis based on the study of Lie symmetries for this system of equations, concentrating our attention on the traveling wave case. We then consider mappings of the resulting reductions onto equations defining elliptic functions, and special cases thereof, for example, solvable in terms of hyperbolic functions. In this way, we construct exact solutions of the system of partial differential equations under consideration. We believe this to be the first analytic study of this particular mathematical model.

scholarly journals Non-local dispersion and ultrasonic tunneling in concentrationally graded solids

2019 ◽  
Vol 21 (1) ◽  
pp. 54-62
Author(s):  
A. B. Shvartsburg ◽  
M. D. Malinkovich ◽  
A. M. Kislyuk
Keyword(s):  
Acoustic Waves ◽  
Travelling Waves ◽  
Ultrasonic Waves ◽  
Formal Similarity ◽  
Constant Elasticity ◽  
Transmittance Spectra ◽  
Local Dispersion ◽  
Total Transmission ◽  
Non Local ◽  
Spectral Ranges

The non-local dispersion of longitudinal ultrasonic waves is shown to appear in the heterogeneous solids due to continuous spatial distributions of their density and/or elasticity (gradient solids). This dispersion gives rise to the diversity of ultrasonic transmittance spectra, including the broadband total reflectance plateau, total transmission and tunneling spectral ranges. The ultrasonic wave fields in gradient solids, formed by interference of forward and backward travelling waves as well as by evanescent and antievanescent modes are examined in the framework of exactly solvable models of media with continuously distributed density and elasticity. Examples of transmittance spectra for both metal and semiconductor gradient structures are presented, and the generality of concept of artificial non-local dispersion for gradient composite materials is considered. It should also be noted that the wave equation for acoustic waves in gradient media with a constant elasticity modulus and a certain predetermined density distribution reduces to an equation describing the electromagnetic wave propagation in transparent dielectric media. This formal similarity shows that the concept of nonlocal dispersion is common for both optical and acoustic phenomena, which opens the way to the direct use of physical concepts and exact mathematical solutions, developed for gradient optics, to solve the corresponding acoustic problems.

Novel method to synthesis ZnO nanostructures via irradiation zinc acetate with a nanosecond laser for photocatalytic applications

2020 ◽  
Vol 31 (12) ◽  
pp. 9835-9845
Author(s):  
Noor J. Ridha ◽  
Firas K. Mohamad Alosfur ◽  
Hiba Basim Abbas Kadhim ◽  
Lazem H. Aboud ◽  
N. Al-Dahan
Keyword(s):  
Zinc Acetate ◽  
Nanosecond Laser ◽  
Zno Nanostructures ◽  
Novel Method ◽  
Photocatalytic Applications

Rectification of Acoustic Waves

1974 ◽  
Vol 52 (17) ◽  
pp. 1726-1730 ◽  
Author(s):  
S. S. Mathur ◽  
M. S. Sagoo
Keyword(s):  
Energy Density ◽  
Acoustic Wave ◽  
Acoustic Waves ◽  
Ultrasonic Waves ◽  
Pressure Amplitude ◽  
The Difference

The difference in the behavior of the denser and the rarer regions of a longitudinal travelling acoustic wave is utilized to produce the phenomenon of rectification of ultrasonic waves. It has been shown that, under appropriate conditions, the energy density of sound in the regions of rarefaction can be increased while in the regions of compression the energy density is decreased. It is found that under suitable conditions, the pressure amplitude in the rarer regions is about 4% larger than that in the denser regions. The measurement of this difference in amplitude can be used to determine the parameter of nonlinearity.

Monitoring the width of hydraulic fractures with acoustic waves

Geophysics ◽  
1998 ◽  
Vol 63 (1) ◽  
pp. 139-148 ◽  
Author(s):  
Jeroen Groenenboom ◽  
Jacob T. Fokkema
Keyword(s):  
Hydraulic Fracture ◽  
Acoustic Waves ◽  
Direct Determination ◽  
Time Lapse ◽  
Ultrasonic Waves ◽  
Hydraulic Fractures ◽  
Slip Model ◽  
Layer Model ◽  
Incident Wavelength ◽  
Linear Slip Model

During scaled hydraulic fracturing experiments in our laboratory, the fracture growth process is monitored in a time‐lapse experiment with ultrasonic waves. We observe dispersion of compressional waves that have propagated across the hydraulic fracture. This dispersion appears to be related to the width of the hydraulic fracture. This means that we can apply the dispersion measurements to monitor the width of the hydraulic fracture in an indirect manner. For a direct determination of the width, the resolution of the signal is required to distinguish the reflections that are related with two distinct fluid/solid interfaces delimiting the hydraulic fracture from its solid embedding. To make this distinction, the solid/fluid interfaces must be separated at least one eighth of a wavelength and represent sufficient impedance contrast. The applicability of the indirect dispersion measurement method however, extends to a fracture width that is in the order of 1% of the incident wavelength. The time‐lapse ultrasonic measurements allow us to relate the small difference in arrival time and amplitude between two measurements solely to the small changes in the width of the fracture. Additional experimental data show that shear waves are completely shadowed by hydraulic fractures, indicating that there is no acoustic contact mechanism at the fracture interface. Therefore we think it is appropriate to use a thin fluid‐filled layer model for these hydraulic fractures instead of the standard empirically oriented linear slip model. Nevertheless, the thin layer model is consistent with the linear‐slip model, if interpreted correctly. A comparison of width measurements inside the wellbore and width estimates by means of dispersion measurements close to the wellbore shows that the method can be successfully applied, at least under laboratory conditions, and that small changes in the width of the fracture are directly expressed in the dispersion of the transmitted signal. This opens the way for the important new application of width monitoring of hydraulic fractures.

scholarly journals Numerical investigation of the effects of smoothing by spectral dispersion on stimulated rotational Raman scattering

2013 ◽  
Vol 31 (1) ◽  
pp. 171-175 ◽  
Author(s):  
X.M. Fan ◽  
Z.W. Lu ◽  
D.Y. Lin ◽  
F. Yang ◽  
Y. Liu ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Gain Coefficient ◽  
Incident Laser ◽  
Temporal And Spatial Variation ◽  
Suppression Effect ◽  
Incident Laser Pulse ◽  
Spectral Dispersion ◽  
Simulation Results ◽  
Temporal And Spatial ◽  
Modulation Degree

AbstractThe effect of smoothing by spectral dispersion (SSD) on stimulated rotational Raman scattering (SRRS) in air has been investigated both numerically and theoretically. The suppression effect of SSD on SRRS process is verified and it is demonstrated and proposed that the suppression effect is attributed to two aspects: the decreasing of the laser fluence modulation degree and the reducing of Stokes gain coefficient caused by the temporal and spatial variation of the phase of the incident laser pulse. The simulation results show that the SRRS threshold distance can be lengthened by choosing appropriate SSD parameters.

Localized Microstructures Fabrication Through Standing Surface Acoustic Wave and User-Defined Waveguides

2019 ◽  
Author(s):  
Yancheng Wang ◽  
Chenyang Han ◽  
Deqing Mei ◽  
Chengyao Xu
Keyword(s):  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Structural Design ◽  
Acoustic Waves ◽  
Biomedical Applications ◽  
Cell Interaction ◽  
Experimental Setup ◽  
Acoustic Waveguides ◽  
Novel Method ◽  
Patterned Microstructure

Abstract Polymer-based substrates with patterned microstructure on the surfaces, e.g., cell culturing scaffolds, have been utilized in biomedical applications. This paper develops a novel method to fabricate the localized microstructure on the polymer-based substrate with the assistance of standing surface acoustic wave (SAW) and user-defined acoustic waveguides. The specific designed acoustic waveguides can localize the standing acoustic waves and transmit to the liquid film and excite patterned microstructures on the surface, then using ultraviolet (UV) to solidify the substrate with patterned microstructures. The structural design and fabrication of the SAW device and three different shaped acoustic waveguides are presented. Then, experimental setup and procedures to verify the polymer-substrate with localized microstructures fabrication are performed. By using the different shape of the acoustic waveguides, several types of patterned microstructures with different morphologies are successfully fabricated. Results demonstrated that the proposed fabrication method is an effective way to fabricate polymer-based substrate with localized patterned microstructures, which may have potential in the research on tissue engineering, cell-cell interaction, and other biomedical applications.

A high-speed-modulated retro-reflector for lasers using an acousto-optic modulator

2003 ◽  
Vol 81 (4) ◽  
pp. 625-638 ◽  
Author(s):  
G Spirou ◽  
I Yavin ◽  
M Weel ◽  
A Vorozcovs ◽  
A Kumarakrishnan ◽  
...  
Keyword(s):  
Laser Beam ◽  
Acoustic Waves ◽  
High Speed ◽  
Incident Beam ◽  
Bragg Diffraction ◽  
Heterodyne Detection ◽  
Incident Laser Beam ◽  
Signal To Noise ◽  
Incident Laser ◽  
Acousto Optic Modulator

We have used an acousto-optic modulator (AOM) to impose a frequency-modulated signal on an incident laser beam. The incident laser beam is focussed into the AOM where it undergoes Bragg diffraction and is then retro-reflected. The diffracted beam is also retro-reflected so that it is diffracted again by the AOM and overlaps the incident beam. The overlapped beams are frequency shifted with respect to each other. These features allow us to detect the frequency-modulated signal with high signal-to-noise ratio using heterodyne detection. Since the optical setup is simple and can be made very compact, this device may be ideal for certain forms of high-speed, free-space optical communication. We demonstrate a 1 MHz data transmission rate in the Bragg regime. We measured the acceptance angle of the device and find that it is limited only by the divergence of the focussed laser beam and the divergence of the acoustic waves in the AOM crystal. We have also studied the range of acoustic frequencies and drive power of the AOM, for which the retro-reflected beam can be detected with adequate signal to noise. PACS Nos.: 42.60.–V, 42.62.Cf, 42.62.Fi, 42.79.Sz, 42.79.Hp

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