Patterned alignment of liquid crystal molecules in silica micro-capillaries

Abstract

Controllable alignment of liquid crystal molecules inside micro-capillaries is an essential issue to obtain repeatable devices based on photonic liquid crystal fibres. In this paper we describe in detail the photo-alignment technique for micro-capillaries based on sulfuric azo dye SD-1 which allows for stable alignment of liquid crystal molecules in the direction defined by the polarisation of ultraviolet light. Two-step selective irradiation allowed for periodic patterns in which two different alignment configurations were observed simultaneously within a single capillary. The obtained alignment was very stable, even in capillaries as thick as 125 μm of internal diameter.

Keywords:

• liquid crystals
• photo-alignment
• patterned alignment
• microstructured optical fibres
• microtubes
• photonic crystal fibres

Acknowledgements

This work was supported by the Polish Ministry of Science and Education under the grant N517 554139 and partially by the ‘Mistrz’ and ‘Start’ Programmes of the Foundation for Polish Science. The support of HKUST grants CERG 612310, CERG 612409 is also gratefully acknowledged.