On the polarization of light diffracted by ultrasound

If light is diffracted by ultrasound in an isotropic medium with acoustically induced birefringence, the state of polarization is modified in each order of diffraction with respect to the initial state of polarization of the incident light wave. In the present paper, some polarization effects are discussed in the case of normal light incidence. In general a rotation of the main polarization plane occurs, together with a change of the ellipticity. However, while the former effect always takes place, the latter only occurs in the case of ultrasonic light diffraction of the intermediate type. Some experimental measurements are included in case of argon laser light being diffracted by an ultrasonic wave propagating in fused silica (SiO2).

Diffraction of light by two ultrasonic beams of frequency ratio 1:2, beyond the Raman-Nath diffraction regime

Light diffraction by two ultrasonic waves of frequency ratio 1:2 is examined beyond the Raman-Nath diffraction regime. Measurements were taken of +/- 1 order diffracted light intensities for some Raman-Nath parameter values, as a function of the phase shift between the sound beams. The experimental results obtained are discussed and compared with relevant theoretical predictions. Within the experimental conditions, a quite good quantitative agreement between the experimental data and the appropriate theoretical expectations is observed.