Angular dependence of the linear and nonlinear electro-optic responses in a polar smectic liquid crystal

ABSTRACT

The analysis of the first, second and third harmonic electro-optical responses (EORs) have been performed for planar samples of the liquid crystal (LC) having a broad temperature range of the $Sm{C}_{\alpha }^{\ast }$ phase. It demonstrated strong dependence on the angle between the polariser and the smectic layers normal. The comparison of these measurements for the smectic LC cells with both homogeneously and random orientation of the director agreed with results of the performed theoretical considerations based on the deformation of both the helix and the indicatrix under applied electric field. For the homogeneously aligned cell, the electro-optical effects are dominated by the strong linear process – in contrast to the unaligned cell, where the second-order EOR is important. The study of angular dependence of the nonlinear EOR allowed for easy separation of linear and nonlinear effects.

Graphical Abstract

KEYWORDS:

• Nonlinear electro-optic responses
• angular dependence
• polar smectic liquid crystal
• chiral liquid crystal subphases

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Science Centre (NCN) Poland under Grant 2017/25/B/ST3/00564.