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1
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Real-Time Acousto-Optic Visualization of Ultrasonic Pulses in TeO_2

100%
Polishko O., Yurchenko A., Pilgun Y., Smirnov E.
Acta Physica Polonica A
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2015
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vol. 127
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issue 1
132-134
EN
The ultrasonic beam features in ultrasonic and acousto-optic devices have a great impact on their characteristics and need to be studied. In the current work, a conventional optical visualization technique was extended to include spatial filtration of the light diffraction pattern and stroboscopic illumination of a unit under test. That enabled very weak light responses from ultrasonic waves to be observed. This technique was applied to studying propagation and reflection of ultrasonic pulses in the TeO_2 crystal, a body of the total internal reflection ultrasonic sensor. Analysis of visualization data has revealed an unexpected conversion of the shear horizontal wave radiated by the transducer into a longitudinal one on its normal reflection from the (001) face of the crystal, which is inexplicable as far as the plane wave theory is concerned. This finding requires further research to be confirmed and explained.
2
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Diffraction of Light by Finite Amplitude Ultrasonic Waves

100%
Adler L.
Acta Physica Polonica A
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2015
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vol. 127
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issue 1
5-9
EN
In the late 1950s the Ultrasonic Group at Michigan State University introduced light diffraction to study distortion of ultrasonic waves in liquids under the direction of Prof. Egon Hiedemann. In this paper some results of these studies will be presented with detailed description of the author's measurements of B/A. The rate at which the harmonics are developed (the wave distortion is an indication of the harmonics present) during the propagation of the initially sinusoidal ultrasonic wave depends on the nonlinearity of the medium. The light which is diffracted by the distorted wave results in asymmetric pattern contrary to the Raman-Nath theoretical prediction. From the light intensity measurements due to the generated second harmonics - filtered out by a metal plate - the nonlinearity parameter B/A was determined. Developments in studying finite amplitude standing ultrasonic waves in a liquid filled cavity will be also discussed. Using light diffraction measurements it was observed that above a threshold amplitude, fractional harmonics of the driver transducer are also generated in addition to the generated harmonics. It was recently observed that above a second threshold value of the driver amplitude the system undergoes chaotic behavior. Further increase of the driver amplitude returns the system from chaos to stable oscillation.
3
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Acoustic Modes Transformation upon Reflection in Tellurium Dioxide Crystal

80%
Polikarpova N., Voloshinov V.
Acta Physica Polonica A
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2015
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vol. 127
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issue 1
96-98
EN
Generation of acoustic shear waves in crystals is one of the main problem of acousto-optics. Launching of the shear waves is much more difficult than the longitudinal modes because of difficulties related to acoustic contact and also because of problems arising from matching of acoustic and electric parameters of piezoelectric transducer. We obtained the transverse waves as a result of longitudinal-shear modes reflection in a crystal. Crystals having the required effect should possess a strong anisotropy of their elastic properties to realize the effective acoustic mode transformation. In this paper, one of the important cases of the acoustic waves reflection is investigated theoretically and experimentally. The research was carried out in the crystal of paratellurite.
4
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Influence of Strong Acoustic Anisotropy on Reflection of Bulk Acoustic Waves in Crystals

80%
Polikarpova N.
Acta Physica Polonica A
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2008
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vol. 114
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issue 6A
A-175-A-182
EN
Propagation and reflection of plane elastic waves in the acousto-optic crystals tellurium dioxide and calomel as well as in the ferroelectric material barium titanate is examined in the paper. The reflection of the waves from a free and flat boundary separating the crystal and the vacuum is investigated in the (001) planes of TeO_2, Hg_2Cl_2, and BaTiO_3 in the case of glancing acoustic incidence on the boundary. The analysis shows that as much as two elastic waves may be reflected from the crystal surface. Energy flow of one of the reflected waves in paratellurite and calomel propagates in a quasi-back direction with respect to the incident energy flow, so that both energy flows are separated by an angle as narrow as a few degrees. It is found that a relative intensity of the unusually reflected wave in the acousto-optic crystals may be close to a unit in a wide variety of crystal cuts. Possible applications of the examined phenomena in acousto-optic devices are discussed in the presentation.
5
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Acousto-Optic Modulator Driven by Surface Acoustic Waves

80%
Kakio S.
Acta Physica Polonica A
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2015
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vol. 127
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issue 1
15-19
EN
In this paper, an introduction to the design, fabrication, evaluation, and application of acousto-optic modulators using the Bragg diffraction of an optical guided wave in a channel optical waveguide due to a surface acoustic wave is provided. First, the surface acoustic wave mode dependence in the acousto-optic Bragg diffraction was discussed by considering the surface acoustic wave power required for the maximum diffraction P_{{100}} calculated using coupled mode theory and the measured P_{{100}} in Ti-diffused planar optical waveguides fabricated on LiNbO_{{3}} substrates. Next, performances of several devices that the author and the coworkers developed are reviewed. These include a waveguide-type acousto-optic modulator using a tapered crossed-channel proton-exchanged optical waveguide on a 128°-rotated Y-cut LiNbO_{{3}} substrate for an optical wavelength of 1.55 μm, a monolithically integrated tandem acousto-optic modulator in which several waveguide-type acousto-optic modulators are connected in tandem on the same substrate, and a waveguide-type acousto-optic modulator in which laser lights of the three primary colors, red, green, and blue, can be modulated by the same modulator at the same driving frequency.
6
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New Acousto-Optic Regime of Interaction in Media Possessing Strong Elastic Anisotropy

80%
Voloshinov V., Djakonov E., Polikarpova N.
Acta Physica Polonica A
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2015
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vol. 127
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issue 1
36-42
EN
We present results on theoretical and first experimental investigation of a new regime of acousto-optic interaction existing in acoustically anisotropic medium. We defined the new regime as "semi-collinear" or "mixed interaction" since it combined properties of the traditional non-collinear diffraction and the pure collinear interaction. The peculiar phenomenon was registered in the tellurium dioxide crystal due to the extremely strong elastic anisotropy of the material. Application of a specific cut of the crystal provided observation of the effect in the middle infrared at the optical wavelength 3.39 μm and at the acoustic frequencies limited to 300 MHz. The observed interaction was characterized by a non-collinear propagation of incident light with respect to acoustic energy flow and simultaneously a collinear propagation of diffracted radiation along the acoustic energy flow. A brief theoretical analysis of the interaction based on wave vector diagrams and two-dimensional coupled wave equations is included in the presentation. Finally, we describe in the paper, the setup and basic details of the carried out acousto-optic experiment.
7
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Acousto-Optical Tunable Transmissive Grating Beam Splitter

80%
Dieulangard A., Kastelik J., Dupont S., Gazalet J.
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EN
We present a tunable transmissive grating beam splitter for multiple laser line separation based on acousto-optic interaction in tellurium dioxide. Acousto-optic devices are well known for light modulation, frequency shifting, filtration or deflection. Unlike the classical operating modes of acousto-optic devices, we consider the simultaneous diffraction of several optical wavelengths by a single ultrasonic frequency. The device is based on the Bragg anisotropic interaction in the specific "tangent phase matching" configuration. The acousto-optic interaction takes place with a single ultrasonic frequency and the diffraction efficiency remains high over a wide optical spectral range. The different diffracted beams are then angularly well separated, due to the slow velocity of the ultrasonic wave propagating in tellurium dioxide. The optical bandwidth is directly related to the operating ultrasonic frequency. Numerical calculations were carried out to determine the main parameters of the device: operating ultrasonic frequency, optical bandwidth, tunability range, crystalline cut and transducer length. A practical device has been designed for visible spectrum. Experimental results are presented as for example a spectral bandwidth from 450 nm to 550 nm with a carrier frequency f_0=125 MHz.
8
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Acousto-Optic Diffraction by Shear Horizontal Surface Acoustic Waves in 36° Rotated Y-Cut X-Propagation Lithium Tantalate

80%
Rimeika R., Čiplys D., Shur M.
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EN
We have investigated the acousto-optic diffraction by shear horizontal surface acoustic waves in 36° rotated Y-cut X-propagation lithium tantalate (LiTaO_{{3}}) crystals. The measurements were performed at the optical wavelength 633 nm of He-Ne laser and acoustic wavelengths of 50-60 μ m. The anisotropic diffraction with the light polarization rotation in the transmission mode was observed. The measured and calculated values of the light incidence angle corresponding to the strongest diffraction differed significantly. A narrow strip of a thin metal film deposited on the crystal surface drastically affected the light diffraction. We attribute these effects to the conversion processes between the shear horizontal leaky surface acoustic wave and shear horizontal surface skimming bulk wave.
9
Content available remote

Influence of Acoustic Anisotropy on Frequency Bandwidths of Bragg Diffraction in Two Orthogonally Polarized Diffraction Orders

80%
Zakharov A., Voloshinov V.
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EN
This paper theoretically and experimentally examines a specific regime of acousto-optic diffraction during which an arbitrarily polarized incident light in a paratellurite crystal is scattered simultaneously into two orthogonally polarized diffraction maxima. We examined acoustic energy walk-off in the crystal and its influence on phase matching as well as on distribution of light energy between the two diffraction orders. This influence was theoretically considered by means of wave vector diagrams illustrating momentum conservation law during the photon-phonon interaction. We obtained expressions for mismatch parameters in the ordinary +1 and extraordinary -1 diffraction orders both depending on the walk-off angle. The obtained parameters were used in the Raman-Nath system of coupled-wave equations to calculate the diffracted light intensities and frequency bandwidths of diffraction. We measured the bandwidths in experiments carried out in the (11̅0) plane of paratellurite crystal at the walk-off angle equal to 54°.
10
Content available remote

An Optical Hydrophone for the Single-Shot Field Measurements of High Power Pressure Pulse Fields

80%
Jamshidi-Rad A., Ueberle F.
Acta Physica Polonica A
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2015
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vol. 127
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issue 1
69-71
EN
The measurements of ultrasonic fields are often performed using polyvinylidene fluoride (PVDF) membrane hydrophones. Recently, optical hydrophones have gained popularity. Refractive type optical hydrophones are based on the change of refractive index at a glass-water interface when the shockwave passes the sensitive area. A major disadvantage of the optical and the PVDF hydrophones is the fact that they provide a single spot sensitive area, with the result that field measurements need a repositioning of the probe. In this work we introduce a multi-spot optical hydrophone with six measurement spots, for the single shot field measurement of shockwave fields. We measure a highly stable shockwave source with a calibrated hydrophone and the multi-spot optical hydrophone and we find good agreement for the calculated energy values of the shockwave field (depending on the energy settings 4{% ± 1{%}).
11
Content available remote

Acousto-Optic Devices Based on Potassium Rare-Earth Tungstates Laser Crystals

80%
Velikovskii D., Pozhar V., Mazur M.
Acta Physica Polonica A
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2015
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vol. 127
|
issue 1
75-77
EN
We present a family of original acousto-optical devices. They are based on new acousto-optical materials KRE(WO_4)_2, where RE = Y, Gd, Yb, Lu. A combination of features such as radiation resistance, optical biaxiality and appreciable acousto-optical figure of merit, makes possible creation of polarization-insensitive modulator with almost 100{% of diffraction efficiency. The deflector with wide angular aperture and broad range of deflection, and collinear tunable filter are also suggested.
12
Content available remote

Optoacoustic Measurements for Small-Volume Liquid Samples

70%
Egerev S.
Acta Physica Polonica A
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2015
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vol. 127
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issue 1
10-14
EN
High sensitivity of optoacoustic measurement method makes it possible to use it for the analysis of the liquid samples having microliter volume. The core of any measurement optoacoustic system is represented by a so-called optoacoustic cell. The paper deals with a layered prism optoacoustic cell. It is well-suited for the small-volume sample analysis. In the paper, laser-induced elastic pulse in the layered prism cell is examined at the stage of its generation, at the stage of its propagation through the body of the cell, and at the stage of the wideband pick-up with the piezoelectric transducer. This pulse serves to determine trace concentrations of various impurities in the sample. The optimization of layered prism cell parameters is proposed. Figures of merit of optoacoustic determination of lipopolysaccharides in the liquid small-volume sample with the use of the optimized layered prism cell are evaluated as an example.
13
Content available remote

From Acoustic Waves to Microwaves

61%
Mendes Pacheco G., Salvi Sakamoto J., Kitano C.
Acta Physica Polonica A
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2015
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vol. 127
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issue 1
25-28
EN
We present here some results of our research related to the optoelectronics and photonics and show all the experimental setups used. Starting with a discussion on the importance of the waves, we demonstrate our achievements based on employment of acoustic, optical, and microwaves and their technological use. The results concern the acousto-optic and electro-optic effects. The generalized analysis of the electro-optic effect reveals a new high induced birefringence in lithium niobate. A patented optical fiber microphone is presented, and its applications to the measurements of acoustic wave velocity in gases and in the laser ultrasound non-destructive evaluation system are discussed. Finally, the generation of microwaves by an optical method with substantial cost reduction is presented.
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