Anisotropy of acousto-optic figure of merit in optically isotropic media

Abstract

We suggest a new approach for analyzing spatial anisotropy of acoustooptic figure of merit (AOFM). The relations for the effective elastooptic coefficients and the AOFM are derived for all possible types of acoustooptic (AO) interactions in optically is otropic media, including non-solid-state and solid -state amorphous media, and crystals belonging to the cubic system. Our approach allows for finding the optimal geometries of AO interactions characterized by the highest AOFM for a given material. The analysis is carried out on the examples of cubic KBr and KAl(SO4)2×12H2O crystals which represent different subgroups of the cubic symmetry class. OCIS codes: 260.1180OCIS codes: 260. , 230.1040OCIS codes: 260. , 160.1050OCIS codes: 260. , 260.1960 http://dx.doi/org/10.1364/AO.99.099999 1.IntroductionAmong the parametric optical effects induced by external fields, such as electro-, magneto-, piezo-and acoustooptic (AO) ones [1,2], AO diffraction represents ma ybe the most frequently used effect. This phenomenon is utilized for deflecting and modulating of light, scanning of the optical beams, RF spectrum analyzing, Q-switching, etc. [3 -6]. It is well known that efficiency of the AO diffraction is d efined by the AO figure of merit (AOFM):where n , ef p and ρ denote respectively the optical refractive index, the effective elastooptic coefficient (EEC) and the density of an optical material, and v the velocity of the acoustic wave (AW). Although the 2 M parameter is scalar, it can reveal notable spatial anisotropy. This anisotropy is mainly influenced by the elastooptic tensor and the tensor of elastic stiffness coefficients, on the basis of which the AW velocities are determined. Anisotropy of the refractive indices contributes to the total spatial dependence of 2 M , too. Thus, the AO efficiency simulta neously depends on a number of constitutive coefficients of a given optical material. Searching for efficient materials for the AO diffraction is of a primary importance. Moreover, development of the methods for analyzing the anisotropy of AO efficiency for different geometries of AO interactions can solve a lot of materials science problems, since the anisotropy of the 2 M coefficient can yield in increasing AO efficiency for both well-known and new materials. As shown in our recent works [7,8], the anisotropy of AW velocities often plays a major role in the anisotropy of AOFM. In fact, it can result in extremely high 2 M coefficient, e.g., for one of the best AO materials, TeO2 crystal [9,10].It is obvious that the EEC and its anisotropy also contribute significantly to the AO efficiency. In particular, this contribution can become notable for the media where the AW velocities are almost isotropic (see, e.g., [11]). Unfortunately, no general method for analyzing the anisotropy of AO efficiency has been developed up to now. To our best knowledge, there have been a few relevant attempts, which are based on the anisotropies of the EEC [12] and the AW velocities [2]. A combined method has been suggested in Ref. [13,1...

Anisotropy of acoustooptic figure of merit for TeO2 crystals. 1. Isotropic diffraction

“…In our recent works [17][18][19] we have developed a method for comprehensive analysis of AOFM anisotropy and have approved it on the example of TeO 2 crystals [18,19]. As a matter of fact, those calculation results agree well with the experimental data.…”

Anisotropy of acoustooptic figure of merit in KH2PO4 crystals

“…To study the anisotropy of AOFM for the KDP crystals, we use the method developed in our recent works [19,20,24,28]. In frame of this method, the anisotropy of AOFM is analyzed issuing from the anisotropy of acoustic and elastooptic properties of a material, using the wellknown relation [29] …”

“…Recently we have developed a general method that allows for determining those directions of propagation and polarization of the optical and acoustic waves (AWs) which ensure maximal AOFM magnitudes [19][20][21][22][23][24][25]. In particular, TeO 2 , LiNbO 3 , -BaB 2 O 4 , NaBi(MoO 4 ) 2 and some others crystals have been studied as examples.…”

Acoustic anisotropy of AgGaGe3Se8 crystals and their acoustooptic applications

“…The same is true of mercury-containing crystals (e.g., Hg 2 Cl 2 [1] or Cs 2 HgCl 4 [2,3]). At the same time, optically isotropic chalcogenide glasses still reveal a restricted diversity of promising AO interactions [10]. The goal of the present work is to begin with large-scale AO studies of the crystalline chalcogenides containing no toxic chemical elements.…”