Light diffraction in an inhomogeneous acoustic field (original) (raw)
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Acousto-optic interaction in a non-homogeneous acoustic field excited by a wedge-shaped transducer
Ultrasonics, 2008
The article is devoted to theoretical analysis of light diffraction in a non-homogeneous acoustic field created by a wedge-shaped piezoelectric transducer. Relationships describing electrical, acoustic and acousto-optic properties of the acousto-optic cell are derived in the approximation of a small thickness of the piezoelectric plate. Principal characteristics of acousto-optic interaction are examined such as dependences of the light diffraction efficiency on the phase mismatch and the acoustic wave amplitude. It is shown that the acoustic field has a complicated amplitude-phase structure changing with the acoustic frequency. It is demonstrated that the diffraction efficiency in the Bragg regime can approach 100% in spite of a noticeable phase mismatch. The appropriate optimal values of ultrasound power and incidence angles of light are found.
Diffraction of light by acoustic waves
Wave Motion, 1985
A method for calculating the intensity of diffracted light by acoustic waves is suggested in the present paper. The solution is obtained as an infinite vector, whose components define the light distribution into different diffraction orders, after the interaction of light with surface or volume acoustic waves. When the acousto-optical interaction takes place in a planar multimode waveguide the solution is given by an infinite matrix with components defining the light distribution both into different diffraction orders and light modes. An additional benefit of the obtained solution is its validity for all regimes of diffraction.
Peculiarities of Acoustooptic Interaction in a Nonhomogeneous Acoustic Field
Ultrasonics International 93, 1993
With the example of an alpha-iodic acid crystal, we demonstrate the unusual peculiarities of acousto-optic interaction in gyrotropic biaxial crystals. Basic attention is given to the most interesting cases of anisotropic diffraction in geometry, when the wave vector of ultrasound is directed almost orthogonally to one of the optical axes, and the directions of incident and diffracted light beams are close to the optical axis. It is shown that in this case a peculiar character of optical anisotropy originates unique variants of acousto-optic interaction that are fundamentally impossible in uniaxial crystals. A wide variety of frequency dependences of the Bragg angles allows choosing optimal configurations of crystal cuts for each specific acousto-optic device. The influence of the effect of optical activity on diffraction characteristics is examined as well.
JOSA A, 1986
Multiple plane-wave scattering techniques are extended to analyze the diffraction of light by adjacent ultrasonics of frequency ratio 1:m to include the near-Raman-Nath regime. This is done first by modifying the existing theory, developed for the diffraction of light by sound at frequency Q, to the general case of light-sound (frequency mg) interaction and thereafter deriving the coupled equations for the diffracted orders in each sound column. Results for some special cases are compared with previously published work.
Ukrainian Journal of Physical Optics, 2021
We report on polarimetric studies for the diffracted light originated from acousto-optic (AO) diffraction at a longitudinal acoustic wave. A particular case of intermediate Bragg-Raman-Nath diffraction regime in fused silica is considered. We find that for the incident circularly polarized optical waves the ellipticity of the diffracted wave is determined by the ratio of elasto-optic coefficients p 11 and p 12 , while for the incident linearly polarized waves this ratio is determined by the azimuth of diffracted wave. The ratio of coefficients determined in this way agrees well with the literature data. We detect a small deviation from linear polarization for the diffracted optical waves under condition when the incident waves are linearly polarized. This deviation can be caused by changing phase difference of the diffracted eigenmodes.
Amplitude measurements of acoustic fields by light reflection at the free surface of a liquid
1995
ABSTRACT A novel technique for amplitude measurements of acoustic field by light reflection at the free surface of a liquid is presented. The motion of the boundary layer of the liquid induced by the acoustic pressure, modulates the phase of a collimated laser beam. This phase modulation is observed using dark-ground techniques, and it gives a measurement of the acoustic power as function of the position. Experiments with piezocomposite 1-3 transducers were carried out. The technique presented is able to give quantitative information quickly about the motion of individual ceramic rods of the piezocomposite, and allows fast quality control for piezocomposite 1-3 transducers. We achieved a lateral resolution of 0.2×0.4 mm. The theoretical limit for the axial resolution is of the order of a few Angstroms
The role of electromagnetic waves in the reflection of acoustic waves in piezoelectric crystals
Wave Motion, 2008
The role of electromagnetic effects in the reflection and transmission of acoustic waves in piezoelectric materials is discussed. Attention is focused on the analysis of a number of situations where the coefficients of plane wave conversion derived on the basis of the electromagnetic theory differ significantly from the coefficients calculated within the frame of the quasi-electrostatic approximation. This effect occurs at quasi-normal incidence for angles of the order of v a /v el , where v a and v el are the typical velocities of the sound and electromagnetic waves, respectively. For instance, according to the electromagnetic description, the acoustic wave must suffer total reflection while the quasi-electrostatic approximation predicts almost total transmission. The possibility of experimental observation of the above effects is also discussed.
Nondiffracting Bulk-Acoustic X waves in Crystals
Physical Review Letters, 1999
The concept of nondiffracting waves is generalized to encompass bulk-acoustic waves within crystalline media. We introduce acoustic Bessel beams and generalized X waves for anisotropic elastic materials. Detailed numerical predictions for propagation-invariant bulk-acoustic beams of various orders, and also X pulses, are presented for experimental verification. The material parameters used have been chosen appropriately for quartz, the most important material for acoustic device applications.