Liquid Crystal Elastomers and Light - Liquid Crystal Elastomers: Materials and Applications - page 94

Liquid Crystal Elastomers and Light

Peter Palffy-Muhoray

Abstract Liquid crystal elastomers (LCEs) are solid liquid crystals; they combine
elasticity with orientational order. Mechanical strain therefore changes liquid
crystalline order and the optical properties of these materials. Conversely, light
can change the orientational order, and give rise to mechanical forces and changes
in shape. Light-matter interactions in LCEs therefore involve a broad range of
unusual phenomena, which raise a number of intriguing questions. There is great
potential for device applications, but considerable challenges must first be over-
come. The most appealing aspect of light-matter interactions in LCEs, however, is
the promise of new physics waiting to be discovered.

Keywords Elastomer Lasing Liquid crystal Orientational order

Photoactuation Photoisomerization Strain

Contents
1 Introduction .................................................................................. 96
1.1 Orientational Order . . . . . . . . . . . . . . . . . . . . . . ............................................. 96
1.2 Elasticity ............................................................................... 98
1.3 Liquid Crystal Elastomers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
2 The Effects of LCEs on Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
2.1 Refractive Indices . . ................................................................... 100
2.2 Polydomain LCEs, Gels, and LC Networks . ........................................ 101
2.3 Lasing in Cholesteric LCEs .......................................................... 102
2.4 Optical Properties of Cholesterics .................................................... 103
2.5 Distributed Feedback Lasing in Cholesteric LCEs .................................. 105
2.6 Non-lasing Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106