Nonlinear optical properties of dye-doped E7 liquid crystals at the nematic–isotropic transition

ABSTRACT

This work shows the influence of a 2,1,3-benzothiadiazole-based dye in the nonlinear optical refraction and nonlinear optical absorption of the thermotropic liquid crystal E7 at the nematic–isotropic transition in the ms time-scale using the Z-scan technique. The addition of dye does not modify the critical exponent of the nonlinear birefringence observed for the undoped sample at the transition, confirming the tricritical character. Also, the order parameter based in the nonlinear absorption shows, for the samples with higher dopings, a critical exponent that deviates from the expected value in the tricritical hypothesis.

Graphical Abstract

KEYWORDS:

• Dye
• phase transition
• Z-scan technique
• thermal lens
• nonlinear absorption
• nonlinear refraction

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Brazilian agencies CAPES, CNPq, FAPESP, Secretaria de Ciência, Tecnologia e Ensino Superior do Paraná and Fundação Araucária and it was conducted as part of the research programme of the National Institute of Science and Technology in Complex Fluids (INCT-FCx), INCT/INEO and INCT-Catlise.