Elucidating the fine details of cholesteric liquid crystal shell reflection patterns

ABSTRACT

Clusters of planar-aligned short-pitch cholesteric liquid crystal spheres generate dynamic colourful patterns due to multiple selective reflections from the radially oriented cholesteric helices in neighbour shells at varying distances. These photonic communication patterns were widely investigated for the cases of both droplets and shells, demonstrating not only intriguing optical phenomena but also potential for applications as new optical elements for photonics, sensing or security pattern generation. However, the optics of these clusters is truly complex and until now only the strongest and most fundamental reflections have been analysed and explained. In this report, we elucidate the origin of a number of more subtle reflections and we explain the extension in space of various spots as well as their internal colour variations.

GRAPHICAL ABSTRACT

KEYWORDS:

• Cholesteric liquid crystals
• spherical reflectors
• photonic communication
• Bragg reflection

Acknowledgments

Financial support from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement n.648763 (consolidator project INTERACT), from the University of Luxembourg (project UNIQUE), and from the Slovenian Research Agency (ARRS) in the framework of the research programme P1-0192 is gratefully acknowledged. J.N. acknowledges support from the Fonds National de la Recherche (FNR, Ph.D. grant ULISCO, code 6992111).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Fonds National de la Recherche Luxembourg [ULISCO/6992111]; H2020 European Research Council [INTERACT/648763]; Javna Agencija za Raziskovalno Dejavnost RS [P1-0192]; Université du Luxembourg [UNIQUE].