The alignment of nematic liquid crystal by the Ti layer processed by nonlinear laser lithography

TL;DR

This paper demonstrates that nonlinear laser lithography can create microstructured Ti layers capable of aligning nematic liquid crystals, offering a fast, cost-effective alternative to traditional alignment methods with comparable anchoring energy.

Contribution

First application of nonlinear laser lithography for nematic liquid crystal alignment using microstructured Ti layers, with detailed analysis of processing parameters affecting alignment quality.

Findings

Microgrooves of about 1 μm period were formed on Ti layers.

Maximum azimuthal anchoring energy comparable to photoalignment.

Polyimide coating enhances anchoring energy.

Abstract

It is well known that the alignment of liquid crystals can be realized by rubbing or photoalignment technologies. Recently nonlinear laser lithography was introduced as a fast, relatively low-cost method for large area nano-grating fabrication based on laser-induced periodic surface structuring. In this letter for the first time the usage of the nonlinear laser lithography as a perspective method of the alignment of nematics was presented. By nonlinear laser lithography, microgrooves with about 1 {\mu}m period were formed on Ti layer. The microstructured Ti layer was coated with oxidianiline-polyimide film with annealing of the polymer followed without any further processing. Aligning properties of microstructured Ti layers were examined with combined twist LC cell. The dependencies of the twist angle of LC cells and azimuthal anchoring energy of layers on scanning speed and power of laser beam during processing of the Ti layer were the focus of our studies as well. The maximum azimuthal anchoring energy, obtained for pure microstructured Ti layer, is comparable with photoalignment technology. It was found that the deposition of polyimide film on microstructured Ti layer leads to the gain effect of the azimuthal anchoring energy. Also, AFM study of aligning surfaces was carried out.