Xue Linpei, Elston Steve J, Morris Stephen M
Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, United Kingdom.
ACS Photonics. 2025 May 5;12(5):2612-2623. doi: 10.1021/acsphotonics.5c00098. eCollection 2025 May 21.
In this paper, we investigate the potential of achieving polarization independent phase modulation using supertwisted nematic (STN) liquid crystal (LC) devices. Here, we describe the use of a burst driving voltage applied to a 180° STN LC device to obtain a twist symmetric H (T-Hs) state, which enables simultaneous modulation of light for all polarizations, demonstrating a polarization independent characteristic in the time domain. Additionally, we consider a 90° twisted nematic (TN) LC device for comparison, as this can also exhibit polarization independent characteristics. Simulations were carried out using a numerical model based on the Ericksen-Leslie continuum equations, which was employed in conjunction with the Jones calculus to simulate the optical properties of the device. The time-dependent optical phase modulation of the device was subsequently measured by using a phase-shifting Mach-Zehnder interferometer. The experimental results demonstrate that an STN device with an 8.9 μm thick LC layer operating in the T-Hs state exhibited a π/2 optical phase modulation in 1 ms for a burst voltage of 30 Vrms that was found to be independent of the incident polarization. These measurements were obtained at room temperature in a single optical path configuration and were found to be in good agreement with the results from the simulations.
在本文中，我们研究了使用超扭曲向列（STN）液晶（LC）器件实现偏振无关相位调制的潜力。在此，我们描述了将突发驱动电压施加到180° STN LC器件上以获得扭曲对称H（T-Hs）状态，该状态能够对所有偏振光进行同时调制，在时域中展现出偏振无关特性。此外，我们考虑使用90°扭曲向列（TN）LC器件进行比较，因为它也能表现出偏振无关特性。使用基于埃里克森-莱斯利连续介质方程的数值模型进行了模拟，该模型与琼斯算法结合使用以模拟器件的光学特性。随后使用相移马赫-曾德尔干涉仪测量了器件随时间变化的光学相位调制。实验结果表明，在T-Hs状态下工作的具有8.9μm厚LC层的STN器件，对于30 Vrms的突发电压，在1 ms内表现出π/2的光学相位调制，且发现该调制与入射偏振无关。这些测量是在室温下单光路配置下获得的，并且发现与模拟结果非常吻合。
