Study of elastic constant ratios in nematic liquid crystals

Abstract

A technique has recently been proposed for determining the elastic constant ratio K22∕K11 in nematic liquid crystals [E. P. Raynes, C. V. Brown, and J. F. Strömer, Appl. Phys. Lett. 82, 13 (2003)]. This technique has been applied to five nematic materials that cover a range of K33∕K11 elastic constant ratio values. An unusually high value of K22∕K11 is found in one material. High values of the ratio K22∕K11 tended to occur in materials that also have high values of the ratio K33∕K11. The results are validated with independent measurements of K22 from cholesteric helix unwinding.

Observation of Self-Induced Optical Vortex Precession

“…5(a)]. The ' 8% difference with the average value of the experimentally measured splay, twist, and bend Frank elastic constants of E7, K ¼ 11:4 pN [27], leads us to conclude that the observed self-induced optical vortex precession regime is reminiscent of the homogeneous bifurcation of a NLC film under a plane wave. A quantitative theoretical description of the observations in their entirety is beyond the aim of the present contribution and appears highly challenging in view of the complexity of the involved physical ingredients.…”

Tunable highly birefringent bandgap-guiding liquid-crystal microstructured fibers

“…6(d)]; while moving toward the weak-anchoring limit (σ = 1), the molecules obtain a uniform alignment parallel to the z-axis. For cylindrical cavities of small radii (r ≤ 0.4 µm), the PP texture is in general promoted, while for larger radii, the ER pattern is more likely to be observed [33]. In the case of the bandgap fiber studied, a set of typical values such as βΛ ≈ 7, n eff ≈ 1.95, and r = 0.25Λ will result in a value of r ≈ 215 nm for the cladding hole radius at an operational wavelength of 1500 nm, suggesting that the PP pattern will be more probably encountered in practice.…”

“…K being the elastic constant and ∆ the static anisotropy of the liquid-crystalline dielectric constant, which for the nematic material E7, obtain the values K = 10.3 pN and ∆ = 13.3 [33]. Equation (2) can be numerically solved using an iterative successive overrelaxation scheme.…”

Liquid crystal-based dielectric loaded surface plasmon polariton optical switches

“…¼ 5:3, and its elastic constants K 11 , K 22 , and K 33 , are taken equal to 10.3 pN, 7.4 pN, and 16.48 pN, respectively. 20 PMMAs relative dielectric constant at low frequencies is equal to 2.6, while that of silica is equal to 3.91. The accurate calculation of the LC molecular reorientation profile requires the solution of the coupled electrostatic/ elastic problem, which involves the minimization of the total energy of the system, as described in detail in Refs.…”