Stretchable liquid crystal blue phase gels

TL;DR

This paper reports the creation of a stretchable blue phase I liquid crystal gel that exhibits strain-tunable optical properties and a Pockels electro-optic effect, opening new avenues for low-voltage optical devices.

Contribution

The first fabrication of a stretchable blue phase I gel with strain-manipulated photonic and electro-optic properties, demonstrating new functionalities in liquid crystalline polymers.

Findings

Stretchable blue phase I gel can be mechanically deformed while maintaining optical properties.

Deformed blue phase exhibits a Pockels electro-optic effect not present in the undistorted phase.

The material's properties can be controlled by strain and applied voltage.

Abstract

Liquid crystalline polymers are materials of considerable scientific interest and technological value to society [1-3]. An important subset of such materials exhibit rubber-like elasticity; these can combine the remarkable optical properties of liquid crystals with the favourable mechanical properties of rubber and, further, exhibit behaviour not seen in either type of material independently [2]. Many of their properties depend crucially on the particular mesophase employed. Stretchable liquid crystalline polymers have previously been demonstrated in the nematic, chiral nematic, and smectic mesophases [2,4]. Here were report the fabrication of a stretchable gel of blue phase I, which forms a self-assembled, three-dimensional photonic crystal that may have its optical properties manipulated by an applied strain and, further, remains electro-optically switchable under a moderate applied voltage. We find that, unlike its undistorted counterpart, a mechanically deformed blue phase exhibits a Pockels electro-optic effect, which sets out new theoretical challenges and new possibilities for low-voltage electro-optic devices.