Acoustic shear wave propagation in Paratellurite with reduced spreading

Abstract

An original configuration of propagation of acoustic shear wave in Paratellurite slightly off the [110] axis in the (001) plane is described. It allows greatly reducing the spreading of the acoustic energy. The main characteristics of an acousto-optic interaction with this acoustic shear wave are then discussed. An experimental validation based on the schlieren method is finally proposed. It shows the effective reduction of the acoustic beam diffraction of the shear wave propagating with a 5° angular tilt. It is compared with the acoustic diffraction obtained for a shear wave propagating in TeO2 along the [110] axis without angular tilt.

Influence of Strong Acoustic Anisotropy on Reflection of Bulk Acoustic Waves in Crystals

“…In this paper, the acousto-optic material paratellurite TeO 2 and calomel Hg 2 Cl 2 were chosen for the analysis. These materials are characterized by the pronounced elastic anisotropy so that the value of the acoustic phase velocity V strongly depends on a direction of propagation [3][4][5][6][7][8][9]. In particular, the slow-shear acoustic wave propagating in the XY plane at the angle θ = 45 • relatively to the axis X or Y possesses the extraordinary low phase velocity values V = 616 m/s, for paratellurite, and V = 347 m/s, for calomel.…”

“…The new effects manifest themselves in the most impressive manner in the modern acousto-optic materials such as paratellurite TeO 2 and calomel Hg 2 Cl 2 as well as in other crystals possessing the extremely strong anisotropy of their elastic properties [1][2][3][4][5][6][7][8][9]. It should be noted that growth and fabrication of these unique crystalline materials was to a great extent stimulated by requirements of acousto-optics, optical communication, and laser technology [1][2][3][4][5][6][7][8][9]. In this paper, the acousto-optic material paratellurite TeO 2 and calomel Hg 2 Cl 2 were chosen for the analysis.…”

“…It may be shown that the walk-off angle ψ between the acoustic wave vector K and the Poynting vector in these materials may exceed dozens of degrees, e.g. ψ > 70 • [1][2][3][4][5][6][7][8][15][16][17][18], while in BaTiO 3 , the angle is limited to ψ > 40 • . This characteristic feature of the waves may cause the strange reflection of the acoustic energy incident on a free boundary separating the materials and the vacuum.…”

“…The elastic waves propagating in the anisotropic crystals, such as paratellurite, and calomel are characterized by large walk-off angles ψ between the phase V and the group V g velocities of ultrasound [1][2][3][4][5][6][7][8][10][11][12][13][14][15]. It may be shown that the walk-off angle ψ between the acoustic wave vector K and the Poynting vector in these materials may exceed dozens of degrees, e.g.…”

Acousto-Optic Characteristics in Media with Strong Acoustic Anisotropy

“…• [1,2]. This anisotropy leads to new eects in AO interaction, changing its angular, frequency and spectral characteristics.…”