Diffractive optical elements based on photoaligned liquid crystals: reflective and transmissive devices with different functionalities

Inge Nys; Miglé Stebryté; Rohan Sharma; Brecht Berteloot; Jeroen Beeckman; Kristiaan Neyts

doi:10.1117/12.3022591

18 June 2024 Diffractive optical elements based on photoaligned liquid crystals: reflective and transmissive devices with different functionalities

Inge Nys, Miglé Stebryté, Rohan Sharma, Brecht Berteloot, Jeroen Beeckman, Kristiaan Neyts

Author Affiliations +

Proceedings Volume 13016, Liquid Crystals Optics and Photonic Devices; 130160A (2024) https://doi.org/10.1117/12.3022591
Event: SPIE Photonics Europe, 2024, Strasbourg, France

Abstract

Diffractive optical elements (DOEs) are increasingly used as miniaturized and lightweight components in photonic devices. Efficient steering of light can be obtained with the help of photoaligned liquid crystal (LC) devices that modulate the geometric phase of light. We study a multitude of diffractive LC structures, ranging from simple one-dimensional gratings with a periodically rotating surface alignment, to highly dispersive gratings, multi-stable gratings and different types of lenses. All these components are enabled by photoalignment technology, that allows to control the geometric phase of the transmitted or reflected light by locally varying the azimuthal anchoring direction of the LC. Next to the standard nematic LCs, we also investigate the use of chiral nematic LCs (with different chiral pitches) and dual-frequency nematic LCs. The use of short pitch chiral LC gives rise to highly efficient diffraction in reflective devices, as we have demonstrated in linear gratings and on- and off-axis lenses. Dual-frequency LC on the other hand allows to substantially enhance the diffraction efficiency over large angles in transmissive devices. Imposing well-designed anchoring patterns at the substrates also allows to obtain highly dispersive configurations or structures with hysteresis switching as a function of the applied electric field. In all case, the working principles of the component can be understood with the help of finite element Q-tensor simulations for the LC director.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Inge Nys, Miglé Stebryté, Rohan Sharma, Brecht Berteloot, Jeroen Beeckman, and Kristiaan Neyts "Diffractive optical elements based on photoaligned liquid crystals: reflective and transmissive devices with different functionalities", Proc. SPIE 13016, Liquid Crystals Optics and Photonic Devices, 130160A (18 June 2024); https://doi.org/10.1117/12.3022591

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