Tuning of Photonic band gap via combined effect of electric and optical fields in a blue phase liquid crystal composite

ABSTRACT

Blue phase liquid crystals are soft 3D photonic crystals in which the liquid crystal molecules self-assemble to form a cubic structure with lattice spacing of a few hundred nanometers resulting in selective reflection of colours in the visible spectrum. The corresponding wavelength or the ‘photonic band gap’ can be tuned using various external stimuli such as thermal, electric, magnetic and optical fields. Here, we report efficient tuning of photonic band gap by utilising the combination of electric and optical fields in a blue phase liquid crystalline system. The studies indicate that the chirality of the medium has a direct bearing on the direction of the wavelength shift and the extent of the photonic band gap tunability. More importantly, the synergistic effect of the two fields helps in reversible tuning of the band gap.

Graphical abstract

(Colour online)

KEYWORDS:

• Blue phase liquid crystal
• photonic band gap
• selective reflection
• photo-isomerisation
• chirality
• solvent polarity

Acknowledgments

One of the authors, GGN gratefully acknowledges funding from SERB (DST) project CRG/2018/000736. GGN & VS acknowledge the financial support from the Thematic project (SR/NM/TP‐25/2016), Nano Mission, Department of Science and Technology (DST), New Delhi, India.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the Department of Science and Technology, Ministry of Science and Technology [SR/NM/TP‐25/2016];Science and Engineering Research Board (DST) [CRG/2018/000736].