Giant optical rotation in piezoelectric crystals with calcium gallium germanate structure

Comparative Interrelationship of the Structural, Nonlinear-Optical and Other Acentric Properties for Oxide, Borate and Carbonate Crystals

“…The optical activity is increased for the crystals with the langasite structure [82,89]. Such giant enhancement can be stipulated by the cavity resonance effect in the nonlinear photonic crystals, by the cross-correlation between magnetic and electric properties (particularly in the BiFeO3 films [88]), by Here, in spite of the high point scattering, the simple linear correlation "lgd-lgr" with "lgr", increasing from some positive proportional values "lgd", is roughly observed.…”

“…Besides, it is necessary to note that the giant enhancement of some "acentric" property is observed, as rule, for a certain value of spontaneous polarization, piezoelectric, electro-optical, nonlinear optical susceptibility or the optical activity of oxide crystals [81,[87][88][89][90]. The optical activity is increased for the crystals with the langasite structure [82,89].…”

“…The optical activity is increased for the crystals with the langasite structure [82,89]. Such giant enhancement can be stipulated by the cavity resonance effect in the nonlinear photonic crystals, by the cross-correlation between magnetic and Crystals 2017, 7, 109 6 of 29 electric properties (particularly in the BiFeO 3 films [88]), by the second-order Jahn Teller effect, and by the enhancement of piezoelectric property near the morphotropic phase boundary (MPB) [72][73][74][75][76][77].…”

“…Here, at the plotting of B-spline line, some points with a high level of values χ (2) > 53 pm/V for oxide crystals ZnTiO 3 , PbVO 3 , BiGaO 3 , BiFeO 3 ,β-LiNbWO 6 are not taken into account because of the absence of their data on the piezoelectric coefficient [68,[76][77][78][79][84][85][86]. In Figure 5, the maximal values of χ (2) are plotted for oxide crystals PbVO 3 (53 pm/V, C 4v ) [68], β-LiWNbO 6 (χ (2) ≈ 70 pm/V, C 3v ) [78][79][80][81][82][83][84][85][86][87][88][89], and our estimation of the values χ (2) for crystals ZnTiO 3 (C 3v ) on the last P s data [76] is also taken into account But, the higher χ (2) -level for the B-spline line very well corresponds to the χ (2) -level of these points. Now the most giant nonlinear optical coefficient d 33 = 3401 pm/V is observed in the multiferroic BiFeO 3 films due to the large ferroelectric polarization (P s = 100 µC/cm 2 ) and coupling between magnetic and ferroelectric order parameters [88].…”

Optical activity along the optical axis of crystals with ordered langasite structure

“…However, their structures are disordered, which causes higher acoustic losses and also non-uniform material properties. Therefore, several new crystals with ordered structure, such as STGS, SNGS, CTGS and CNGS, were synthesized and investigated [5][6][7][8][9][10][11][12]. All disordered and ordered crystals belong to point group 32 with the general formula of A 3 BC 3 D 2 O 14 [13] .…”