Influence of light polarization on characteristics of a collinear acoustooptic diffraction

The collinear acoustooptic diffraction of arbitrarily polarized radiation is studied. It is shown that the spectrum of diffracted light at the exit of an acoustooptic cell generally consists of four components, which have different frequencies and polarizations. Beats of these components lead to the modulation of the light passed through an analyzer installed at the exit of the system. Dependences of the amplitudes of components of the passed radiation on the frequency and power of an acoustic wave are studied for different orientations of the polarizer and analyzer.

     

Acousto-optic interaction in a non-homogeneous acoustic field excited by a wedge-shaped transducer

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.     

Light Diffraction on Ultrasound in a Spatially Periodic Acoustic Field

Optics and Spectroscopy - Characteristic features of anisotropic light diffraction in a spatially periodic acoustic field created by a sectioned piezoelectric transducer with antiphase excitation...     

Anisotropic light diffraction in crystals with a large acoustic-energy walk-off

The influence of energy walk-off in an acoustic beam on the characteristic of anisotropic Bragg diffraction of light has been investigated by the example of paratellurite crystal. The angular and frequency characteristics of acousto-optic diffraction have been calculated in wide ranges of ultrasound frequencies and Bragg angles using the modified Raman-Nath equations. It is shown that the walk-off of an acoustic beam may change (either widen or narrow) significantly the frequency and angular ranges. The calculation results have been experimentally checked on an acousto-optic cell made of 10.5°-cut paratellurite crystal.     

Application of tangential geometry of the acousto-optical interaction to visualization of phase objects

A method of visualization of phase objects is described based on selective properties of the Bragg diffraction of light by ultrasound. The main attention is focused on specific features of visualization in tangential geometry of the acousto-optical interaction. It is shown that, in the optimized case, the light intensity distribution in the visualized image is proportional to the phase gradient. The resolution and contrast of the visualized image are analyzed numerically. Potentialities of the method are illustrated by examples of computer simulation of the visualization effect.     

Electrical Control of the Frequencies of a Fabry–Perot Acoustic Resonator

The effect electronic tuning has on the frequency of the acoustic resonance of an acousto-optic modulator intended for active laser mode locking is studied theoretically and experimentally. The problem of exciting a Fabri–Perot acoustic resonator with a plate-like piezoelectric transducer is solved in the approximation of plane acoustic waves, with allowance for the real parameters of the HF generator and the matching elements of the transducer and the generator. Expressions for the basic electrical and acoustic parameters are obtained. Theoretical analysis confirms the frequency shift effect of acoustic resonances, observed earlier experimentally upon varying the matching electrical elements. The experiment is performed using an acousto-optic quartz cell and a lithium niobate transducer.     

Collinear diffraction of divergent optical beams

Two variants of anisotropic collinear diffraction of light on a sinusoidal diffraction grating are studied theoretically with forth and back light scattering relative to the direction of the incident beam. For both variants, two-dimensional transfer functions are calculated and their modification with optical wavelength and diffraction grating period is analyzed. The dependence of integral diffraction efficiency and filter passband on optical beam divergence is examined.