Non-linear electro-optical effects in the study of the helical smectic liquid crystals

Abstract

Measurements of the non-linear electro-optical effects for the well-known prototype liquid crystal material (MHPOBC) are presented. The method to identify liquid crystalline phases and to determine temperatures of phase transitions based on the analysis of the second harmonic component of electro-optical response spectra is used. Applying that method, the values of the frequency ($f_{\mathrm{e}\mathrm{x}\mathrm{t}}$) at which the second harmonic electro-optic response (EOR) possesses an extremum are determined for each smectic phase. We suggest that this characteristic frequency correspond to the phase-type mode processes. Furthermore, we show that the usually neglected results on heating can be useful in discussions of dynamical behaviour of second harmonic EOR in case of smectic phases.

Keywords:

• non-linear electro-optical spectra
• second-order electro-optic response
• smectic subphases
• phase transitions
• MHPOBC

Disclosure statement

No potential conflict of interest was reported by the authors.