Orientational Optical Nonlinearity of Liquid Crystals

Signal processing by opto-optical interactions between self-localized and free propagating beams in liquid crystals

“…Recently, the highly non local and nonresonant molecular response of undoped nematic liquid crystals (NLC) has enabled the demonstration of stable (2+1)-dimensional spatial solitons (or nematicon 12 ) and their interactions at mW power levels. 12,13,14,15,16 In this Letter, based on the large molecular nonlinearity of NLC (several orders of magnitude higher than in CS 2 ), 17,18 we demonstrate all-optical readdressing of spatial solitons via the lens-like perturbation induced by an external beam propagating across the medium.…”

Spatial Solitons in Liquid Crystals

“…In figure 5A the guided TM mode profile H y (x) is presented for the initial homeotropic orientation θ(x)=π/2 (curve '1') and for the light power strong enough to reorient liquid crystalline layer (curve '2' and corresponding to this field the orientation angle θ(x)). All theoretical curves presented in this article were obtained for parameters corresponding to 6CHBT (4-trans-4'-n-hexyl-cyclohexylisothiocyanatobenzene) nematics: ε || =(1.69) 2 , ε ⊥ =(1.52) 2 for wavelength λ=842 nm. Due to the large anisotropy of LCs, the guided mode is changing its profile significantly, when LC reorients (compare curves '1' and '2' in Fig.5A).…”

“…Therefore, they are important optical materials for numerous applications in modern optoelectronics [1]. Liquid crystals are also excellent medium for nonlinear optics [1][2][3]. The main contribution to nonlinear optical phenomena in liquid crystals arises from thermal and reorientation processes.…”

Effect of surface treatment on molecular reorientation of polymer-stabilized liquid crystals doped with oligothiophene

“…[8][9][10][11][12][13][14] In contrast, a photophysical process exploits the nonlinear optical (NLO) effects of an LC. 7,15 When a homeotropic LC is vertically irradiated with linearly polarized light, the interaction between the optical field and the LC molecules generates a torque to rotate the molecular director along the polarization direction, leading to homogeneous (in-plane) orientation. On the other hand, rotation of the molecular director is disturbed both by the interaction between LCs and the glass substrate surface, a process which is also called surface anchoring, and by bulk elasticity.…”

“…However, molecular reorientation triggered by an optical field has attracted attention because it enables the development of all-optical devices. 7,8 Such photoinduced molecular reorientation includes photochemical and photophysical processes. Photochemical processes control LC orientation through a photochemical reaction, for example, photoisomerization, photocrosslinking or photodegradation.…”