Kerr effect at high electric field in isotropic phase of mesogenic materials

TL;DR

This paper explores nonlinear effects in the Kerr effect at high electric fields in isotropic mesogenic materials, revealing faster birefringence growth and temperature-dependent behavior due to dielectric permittivity nonlinearities.

Contribution

It predicts and experimentally observes nonlinear Kerr effect features at high electric fields, including superquadratic birefringence growth and a field-dependent critical temperature.

Findings

Birefringence grows faster than quadratic with electric field.

The birefringence dynamics slow down at high fields.

The critical temperature increases with the square of the electric field.

Abstract

The well-known Kerr effect in isotropic fluids consists in the appearance of uniaxial orientational order and birefringence that grows as the square of the applied electric field. We predict and observe that at a high electric field, the Kerr effect displays new features caused by nonlinear dependence of dielectric permittivity on the field-induced orientational order parameter. Namely, the field-induced birefringence grows faster than the square of the electric field; the dynamics of birefringence growth slows down as the field increases. As a function of temperature, the field induced birefringence is inversely proportional to the departure from an asymptotic critical temperature, but this temperature is no longer a constant (corresponding to the lower limit of the supercooled isotropic phase) and increases proportionally to the square of the electric field.