Switching effects of dual frequency liquid crystals in grating devices

Garry A. Lester; Adrian M. Strudwick

doi:10.1117/12.2609549

3 March 2022 Switching effects of dual frequency liquid crystals in grating devices

Proceedings Volume 12023, Emerging Liquid Crystal Technologies XVII; 1202307 (2022) https://doi.org/10.1117/12.2609549
Event: SPIE OPTO, 2022, San Francisco, California, United States

Abstract

Switchable optical elements incorporating polymer structure and a liquid crystal material offer devices with a voltage controlled phase difference at low cost. The polymer structure may be fabricated using established replication techniques. Earlier work has demonstrated such devices with good optical quality and high diffraction efficiencies. Such a material allows the director to be actively driven either towards homeotropic or planar alignment depending upon the frequency of the drive waveform. For this investigation devices were fabricated using a dual frequency liquid crystal with a polymer structure. Use of a liquid crystal material with a dielectric anisotropy inversion has the advantage in this case that the liquid crystal orientation is less dependent upon surface forces for switching effects. Liquid crystal reorientation and therefore optical switching is field driven into different orientations. Measurement s of the intensity of the transmitted diffraction orders as a function of time were carried out as means to compare the liquid crystal reorientation times for devices with different gratings. The same devices were driven in two ways; changing driving frequency so switching was always field driven or by changing applied voltage so that switching was partly determined by surface forces. It would be expected to observe faster optical switching due to an applied field; this was not always observed to be the case, this may be due to differences in the initial state between field dominated and surface force dominated initial conditions. Work to understand this more fully is in progress.

Conference Presentation

Citation Download Citation

Garry A. Lester and Adrian M. Strudwick "Switching effects of dual frequency liquid crystals in grating devices", Proc. SPIE 12023, Emerging Liquid Crystal Technologies XVII, 1202307 (3 March 2022); https://doi.org/10.1117/12.2609549

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