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1.
Bragg’s acoustooptic diffraction in an acoustically anisotropic medium is considered taking into account the two-dimensional
spatial diffraction structure of the acoustic beam. The conditions are determined under which reverse transfer of optical
power from the diffracted to the transmitted beam in the regime of 100% efficiency of diffraction is considerably suppressed.
It is shown that this effect is due to diffraction bending of wave fronts of the acoustic beam in the acoustooptic diffraction
plane. The problem of optimization of the piezoelectric transducer size and the spatial position of the input light beam is
solved using the criterion of the minimal required power of the acoustic field. The results of simulation in a wide range
of the acoustooptic interaction parameters for a Gaussian light beam are reported. The correctness of the model is confirmed
experimentally. Recommendations for designers of acoustooptic devices are formulated. 相似文献
2.
Diffraction of light by acoustic waves that are generated in the acoustooptic cells of piezoelectric transducers with complex geometry is studied. The diffraction by acoustic beams with triangular, quadrangular (rhombic), hexagonal, etc., cross sections, when the lengths of light-sound interaction in the cross-sectional area of the light beam are different, is considered in the plane wave approximation. The difference in the length of interaction affects the instrument function of acoustooptic devices and provides the suppression of the side lobes in their transmission function. The advantages of using cells with complex-geometry transducers in tunable acoustooptic filters that are incorporated into fiber-optic communication lines with wavelength-division multiplexing (WDM) are discussed. 相似文献
3.
The characteristics of an acoustooptic cell optimized for a tunable filter making it possible to analyze optical images in
the UV range (λ = 200–400 nm) are studied. The attenuation of a slow shear acoustic wave in the (010) plane of the crystal
is measured. It is shown that attenuation of ultrasound affects the filtering characteristics at frequencies f > 500 MHz. Analytical and experimental data are presented, and factors influencing the quality of images obtained with KDP-based
acoustooptic filters are discussed. 相似文献
4.
G. V. Kulak 《Technical Physics》1997,42(9):1055-1057
An intermediate regime for the diffraction of light on ultrasound in gyrotropic anisotropic and cubic crystals in an external
electric field is considered. A system of equations of the coupled waves, which describes acoustooptic diffraction in gyrotropic
anisotropic crystals with consideration of the electrically induced optical anisotropy for a strong interaction between light
and ultrasound, is presented. An intermediate regime for the diffraction of light on ultrasound in gyrotropic anisotropic
crystals which is close to the Bragg regime for a weak acoustooptic interaction is studied. It is shown that the diffracted
light is elliptically polarized and that the ellipticity and polarization azimuth of the diffracted wave depend on the anisotropy
of the photoelasticity, the electrically induced anisotropy of the crystal in the external electric field, the gyrotropy,
and the asymmetry of the diffraction structure.
Zh. Tekh. Fiz. 67, 80–82 (September 1997) 相似文献
5.
A. S. Zadorin 《Russian Physics Journal》1999,42(1):115-122
A theoretical discussion is presented on strong Bragg acoustooptic interaction AOI of light beams in the dynamic field of
an acoustic signal. A system of integrodifferential equations is formulated to describe the evolution of the angular and frequency
spectra of the beams in the AOI region for a high level of acoustooptic coupling. The third-order approximation in the perturbation
method is used to obtain an analytic solution. Calculations are presented on the modulation of monochromatic beams by acoustic
pulses having rectangular envelopes and propagating in a lithium niobate crystal, and the same for a signal having linear
frequency modulation LFM in a paratellurite crystal, which demonstrate the broadening of the beam spectrum as the depth of
the acoustooptic coupling increases, together with the occurrence of an asymmetry specific to strong AOI in the response of
the light field to the symmetrical acoustic signal.
Tomsk State University for Control Systems and Electronics, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii,
Fizika, Vol. 42, No. 1, pp. 99–106, January, 1999. 相似文献
6.
E. A. Turov 《Journal of Experimental and Theoretical Physics》1997,85(4):797-803
This paper discusses the acoustic diffraction of light in the presence of an exchange-enhanced photoelastic interaction of
aniferromagnetic origin resulting from acoustic modulation of the dielectric permittivity due to oscillations in the antiferromagnetism
vector L. In the “easy-plane” type of antiferromagnet these oscillations arise from antiferromagnetoelastic interactions, and can
be so large that the photoelastic interaction corresponding to them can be comparable in value to (or even exceed) the interaction
in well-known nonmagnetic crystals actually used in acoustooptic devices. The advantage of antiferromagnets lies in the fact
that both the diffraction angle and the amplitude of the diffracted light can depend on the magnitude and direction of a magnetic
field in these materals. Here the Raman-Nath diffraction regime is discussed, which is probably more favorable from an experimental
point of view for the antiferromagnets in question. It is shown that for these materials, the usual mechanism of photoelastic
interaction associated with acoustic modulation of the index of refraction is accompanied by an additional mechanism arising
from modulation of the polarization of the optical modes. Qualitative estimates are given for FeBO3.
Zh. éksp. Teor. Fiz. 112, 1464–1475 (October 1997) 相似文献
7.
介绍声光效应的最新理论进展。采用光栅假设,对各向同性介质中的声光效应作了简要讨论,导出了第m级衍射光的衍射效率公式。研究和介绍一种新的声光效应实验装置。在实验中,应用线阵CCD光强分布测量仪等,通过改变超声波的频率和功率,分别实现了对激光束方向的控制和强度的调制;定量给出了声光偏转量的关系曲线和声光调制测量的关系曲线。实验表明,在布喇格衍射下,通过固定超声波功率,测量衍射光相对于零级衍射光的相对光强与超声波频率的关系曲线,不仅可以计算声速,还可以确定声光器件的带宽和中心频率。 相似文献
8.
V. I. Balakshii V. B. Voloshinov G. A. Knyazev L. A. Kulakova 《Technical Physics》2008,53(10):1336-1343
The optical, acoustic, and acoustooptic properties of tellurium crystals viewed as a candidate material for mid-and far-IR
acoustooptic devices are considered. The phase velocities, polarization, and drift angles of the acoustic energy in different
crystal planes are calculated. The acoustooptic figure of merit for tellurium under the anisotropic diffraction conditions
is estimated, and light-sound interaction geometries promising for acoustooptic applications are discussed. Measuring data
for the optical and acoustooptic parameters of tellurium crystals are given. 相似文献
9.
S. N. Sharangovich 《Russian Physics Journal》1995,38(4):364-371
A theoretical model is presented for the strong two-dimensional acoustooptic interaction (AOI) of finite-size beams with arbitrary profiles in an acoustic field with a curved wave front. Transfer functions are derived in a universal normalized form for the AOI. The results of numerical simulation of the diffraction characteristics show that during AOI in an acoustic field with a curved wave front the product of the diffraction efficiency and bandwidth increases at least 1.5 times for a weak interaction and more than five times for a strong interaction. The optimal values of the normalized parameters (of the acoustooptic coupling and the curvature), for which the efficiency and bandwidth are maximum, are determined.Tomsk State Academy of Control Systems and Electronics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 41–50, April, 1995. 相似文献
10.
M. M. Mazur D. Yu. Velikovskii F. A. Kuznetsov L. I. Mazur A. A. Pavlyuk V. E. Pozhar V. I. Pustovoit 《Acoustical Physics》2012,58(6):658-665
The elastic and photoelastic properties of a potassium-gadolinium tungstate KGd(WO4)2 crystal are determined. A complete matrix of elastic constants for the material is obtained for the first time and the velocity diagrams in the five most practically important planes are constructed on its basis. The coefficients of acoustooptic quality M 2 are measured for the first time for the crystal in the case of isotropic diffraction for all basic configurations of acoustooptic interaction, which makes it possible to reveal the directions of the most effective interaction. 相似文献
11.
V. M. Kotov 《Technical Physics》1997,42(7):769-774
Planar acoustooptic 2×2 directional couplers that switch optical rays with different wavelengths are considered. A method
for calculating the angular and frequency characteristics of such switches is developed, and the parameters of a switch based
on a planar Ti-LiNbO3 structure are calculated. Experiments employing bulk acoustooptic diffraction in TeO2 are performed, confirming the basic theoretical assumptions. It is shown experimentally that the best conditions for switching
optical rays directed into optical fibers can be provided nearly always by varying the diffraction angles and the frequencies
of the sound waves. The functional possibilities of the 2×2 directional coupler investigated in a fiber-optic gyroscope are
described.
Zh. Tekh. Fiz. 67, 57–62 (July 1997) 相似文献
12.
Kenji Kajiyama Susumu Hata Seizou Sakata 《Applied Physics A: Materials Science & Processing》1978,16(2):155-158
Dynamic characteristics of laser diodes are numerically calculated on multi-mode rate equations, including spatial relaxing
interaction causing mode competitions or jumps. It is revealed that the interaction effect is classified into three cases
[“independent (or inhomogeneous)”, “competition (or intermediate)”, and “monopoly (or ideally homogeneous)”], that an optimum
relaxing coefficient value exists to minimize relaxation oscillations in rise and decay transients, and that the optimum value
is related to the relaxation period. Calculated results are discussed in comparison with the experimental results. 相似文献
13.
A. S. Zadorin 《Optics and Spectroscopy》2000,88(4):623-629
Based on a spatially dependent dynamic optical transfer function of an acoustooptic modulator, a dynamic model of light modulation by a sound signal under conditions of acoustic damping is developed. A system of equations describing the dynamics of the acoustooptic interaction is given. Solutions of this equation for arbitrary power level and spatial-time structure of a sound signal are found. It is shown that acoustooptic damping has the strongest effect in a nonlinear modulation regime. Here, the dissipation of an acoustic signal suppresses the higher harmonic of the dynamic optical transfer function. An analytical model of the dynamic optical transfer function for a low level of acoustooptic coupling is given. It is shown that when the pump beam aperture is much greater than the spatial size of an acoustic signal, the time response of the acoustooptic modulator response is identical within a phase factor to the amplitude profile of a pump beam apodized by the exponential dependence of the amplitude of a damped sound wave. Otherwise, the sound damping produces almost no distortions of a plane top of the acoustooptic modulator response to a pulsed signal and shows itself only under phase mismatch conditions. Here, the asymmetry of overshoots at the edges of the acoustooptic modulator response is observed. Calculated plots are presented, which illustrate the aforementioned specific features of the transient process under conditions of acoustic damping in the acoustooptic interaction in paratellurite. 相似文献
14.
The theory of acoustooptic interaction of beams taking into account the drift and spreading of beams in an anisotropic medium is presented. The problem is solved analytically for a weak interaction of Gaussian beams close to forbidden directions. The possibility of existence of collinear diffraction of wave beams along the direction forbidden for interaction of plane waves is shown theoretically. The interaction appearing close to such a direction was found to result in a certain distortion of the beam shape. The calculation performed for a paratellurite crystal shows that the efficiency of the diffraction along the forbidden direction can reach 10% at the acoustic power usually used. 相似文献
15.
We obtain equations for the Bragg regime of acoustooptic diffraction of light in two-dimensional photonic crystals. We determine
applicability conditions of the single-wave approximation, in which it is sufficient to take into account only one Fourier
component of each of Bloch waves involved in the acoustooptic interaction. In the single-wave approximation, we obtain formulas
that make it possible to estimate the acoustooptic figures of merit of a photonic crystal. We show that, in a photonic crystal,
higher acoustooptic figures of merit can be achieved than in the materials that make up the crystal. 相似文献
16.
V. M. Kotov 《Technical Physics》1997,42(2):181-185
The principles of acoustooptic switching of two light beams of different wavelengths by means of an acoustooptic interaction
with two acoustic waves are examined. A version in which the acoustic waves form parallelograms and a version with strictly
orthogonal propagation are considered. The latter version is the more attractive one when a TeO2 single crystal is used as the acoustooptic cell. Experiments on the switching of two-color Ar laser radiation with wavelengths
λ1=0.5145 and λ2=0.488 μm are carried out and demonstrate a high switching efficiency. On the whole, the experiment confirms the basic conclusions
of the theory.
Zh. Tekh. Fiz. 67, 66–71 (February 1997) 相似文献
17.
18.
V. R. Zemskov 《Russian Physics Journal》1997,40(9):821-827
The interaction of fast magnetoacoustic (FMA) waves in a plasma with particle concentration nt∼ni∼1 cm−3 is studied with allowance for Alfvén modes, which simulates turbulence. Equations that describe three-wave interaction of
FMAs are derived and a method is indicated for constructing some stationary structures that form in the spatial synchronism
of interacting FMA waves. The applicability of the inverse scattering problem method to the problem of the interaction of
FMA waves in a turbulent plasma is discussed.
Chechen State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, p. 3–9, September, 1997. 相似文献
19.
The most annoying problem relating to the sensitivity of mask inspection systems is the encountering of false signals arising
from nuisance defects. In order to overcome this problem, we have previously proposed a new algorithm for die-to-wafer-like
image (D-to-WI) in real time. This paper describes the optimum mask inspection optics for the D-to-WI mask inspection. We
examine the optimum mask inspection optics with numerical simulation for various numerical apertures (NAs) and partial coherence
factors (σ) in these optics. The simulated result shows that the optimum mask inspection optics for the D-to-WI mask inspection has
NA 0.9 and σ = 0.95 for an ArF-6%-phase shift mask (PSM) 260/260 nm line/space pattern on the mask plane, in which the 193 nm-ArF scanner
has NA 0.93, σ = 0.92 − 0.92/0.3 annular illumination, reduction factor of ×4, and circular polarization incident light. 相似文献
20.
The total charge of the projectile spectator fragments, Qpf is taken as a measure of the degree of centrality of collision thus defining the collision geometry. In this paper the mean
multiplicities of the different charged secondaries emitted in the interaction of 24Mg-Em at 4.5A GeV have been investigated as a function of the total charge Qpf of the projectile spectator fragments. It has been observed that the average number of the produced particles, 〈Ns〉 and the heavily ionizing particles, 〈Nh> decreases exponentially with the increase of Qpf showing strong correlation with the geometry of the collision. An attempt has also been made to compare these results with
84Kr-Em interaction at 0.95A GeV. 相似文献