Optic, acoustic and acousto-optic properties of tellurium in close-to-axis regime of diffraction

Abstract

We examined the optic, acoustic, photoelastic and acousto-optic (AO) properties of single crystal tellurium. We also determined the Bragg angle dependences on the acoustic frequency at 10.6 μm. The phenomenon of optical activity and its influence on the Bragg matching condition during anisotropic diffraction near the optic axis of the crystal are discussed in detail. Based on the results of our calculations, we designed, fabricated and characterized an AO cell to determine parameters of the anisotropic interaction with longitudinal acoustic waves propagating along the X axis in the crystal. In our experiments, we also measured the value of one of the important photoelastic coefficient in tellurium, p 41 =0.14±0.01 and demonstrated that this coefficient determines the efficiency of the anisotropic diffraction in the employed geometry.

Optimal Design of an Ultrasound Transducer for Efficient Acousto-Optic Modulation of Terahertz Radiation

“…The power consumption required to achieve a given level of modulation depth is also important. Therefore, the diffraction efficiency is normalized to the active electrical power [ 14 , 15 ]: where is the diffraction efficiency per 1 W of the electrical power; U is the voltage amplitude on the sound transducer; and are the real part and absolute value, respectively, of the frequency dependent impedance of the sound transducer.…”

“…To estimate the efficiency of AO diffraction, one can use the relation obtained within the simplest model of AO interaction [ 14 ] (which assumes the diffraction of a plane electromagnetic wave by an infinite sound column), introducing in it the additional exponential term considering the ultrasonic attenuation: where is the AO figure of merit; is the acoustic power, which is usually considered as equal to the RF driving power ; d and L are the width and length of the sound transducer; is the sound power attenuation coefficient; l is the distance from the sound transducer at which the THz beam travels (in our experiment cm). The dependence of physical properties of liquefied SF on the temperature and pressure are summarized in work [ 4 ].…”

Polarization of Acoustic Waves in Two-Dimensional Phononic Crystals Based on Fused Silica

“…Monocrystalline materials take a special place in the field of acousto-optics. Among the most common and frequently used media are crystals of tellurium (Te), lithium niobate (LiNbO 3 ), and TAS (Tl 3 AsSe 3 ), as well as various mercury compounds [ 7 , 8 , 9 , 10 ]. Nowadays though, a paratellurite (TeO 2 ) crystal is used as a working material in acousto-optic devices most of the time.…”

Acoustic and acousto-optic properties of Ge-=SUB=-a-=/SUB=-Se-=SUB=-b-=/SUB=-Te-=SUB=-c-=/SUB=- and Si-=SUB=-a-=/SUB=-Se-=SUB=-b-=/SUB=-Te-=SUB=-c-=/SUB=- glasses in case diffraction on longitudinal and shear acoustic waves

“…Currently many materials are considered in the literature as the basis for AO interaction in the medium and long wavelength ranges. They include a tellurium crystal [7,8], cubic crystals based on thallium halides (KRS) [9][10][11], as well as mercury-based compounds: calomel, bromide and mercuric iodide [12].…”