Switchable polarisation-independent blue phase liquid crystal Fresnel lens based on phase-separated composite films

ABSTRACT

A simple method for fabricating a polarisation independent blue-phase liquid crystal Fresnel lens (BPLCFL) is demonstrated by utilising the photo-polymerisation-induced phase separation. The BPLC/polymer binary Fresnel zones is obtained well by periodic UV illumination with phase separation of the BPLC molecules and UV-curable pre-polymer mixture. The diffraction efficiency can be controlled when applying a uniform electric field which modulates the phase difference between even and odd Fresnel zones. Experimental results show that the maximum diffraction efficiency reaches 24.3%, which is close to the measured diffraction efficiency of the used Fresnel zone-plate mask of 25%. We also characterise the tunable lens performance at different applied voltages.

Graphical Abstract

KEYWORDS:

• Blue phase liquid crystal
• Fresnel lens
• photo polymerisation-induced phase separation
• diffraction

Acknowledgements

This research was supported by grants from the Scientific and Technological Research Council of Turkey (TUBITAK) to N. Avci and the Ministry of Science and Technology of The Republic of China, Taiwan (MOST 104-2918-I-239-001-) to S.-J. Hwang. The authors also sincerely acknowledge Prof. Shin-Tson Wu of the University of Central Florida for technical assistance and providing the liquid crystal material and instruments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by grants from the Scientific and Technological Research Council of Turkey (TUBITAK) to N. Avci and the Ministry of Science and Technology of The Republic of China, Taiwan [MOST 104-2918-I-239-001-] to S.-J. Hwang.