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Enhanced Speed and Tunability of Liquid Crystals in Nanocavities via Engineering the Local Electromagnetic Field
ACS Photonics ( IF 6.5 ) Pub Date : 2025-01-23 , DOI: 10.1021/acsphotonics.4c01916
Abu Aisheh Majd, C. K Amaljith, Abdulhalim Ibrahim
ACS Photonics ( IF 6.5 ) Pub Date : 2025-01-23 , DOI: 10.1021/acsphotonics.4c01916
Abu Aisheh Majd, C. K Amaljith, Abdulhalim Ibrahim
The speed of nematic liquid crystals (LCs) is usually limited by the viscoelastic relaxation time, determined by the viscosity, elastic constant, and device thickness. Here, we demonstrate breaking this limit by confining the LC in a resonant nanocavity and designing the electromagnetic field to be concentrated within a specific region of the LC where the molecules react strongly to the applied voltage. Confining the LC within a subwavelength deep silicon (Si) grating of 712 nm height and 566 nm space, we achieve a guided mode resonance that results in high field confinement at the center of the LC space at the resonance wavelength. Conversely, outside the resonance wavelength, the field confinement shifts to the Si lines. This configuration reduces the rise time by an order of magnitude, from 2 ms to 200 μs at the resonance wavelength. The optimized field overlap integral at the center of the LC space indicates that most of the light–matter interactions occur in this region. As a result, this central region responds faster to an increasing voltage than does the entire LC region, thereby explaining the faster response observed at resonance. Similarly, the tunability in response to voltage and temperature can be enhanced if the alignment inside the nanocavities is better controlled. This method paves the way for ultrafast devices that utilize faster LC modes and innovative resonant nanocavity designs.
中文翻译:
通过设计局部电磁场提高纳米腔中液晶的速度和可调性
向列液晶 (LC) 的速度通常受粘弹性弛豫时间的限制,粘弹性弛豫时间由粘度、弹性常数和器件厚度决定。在这里,我们通过将 LC 限制在共振纳米腔中并将电磁场设计为集中在 LC 的特定区域内来展示突破这一限制,在该区域中,分子对施加的电压产生强烈反应。将 LC 限制在 712 nm 高和 566 nm 空间的亚波长深硅 (Si) 光栅内,我们实现了导模谐振,从而在谐振波长处在 LC 空间中心产生高场限。相反,在谐振波长之外,场限制会转移到 Si 线。这种配置将谐振波长处的上升时间缩短了一个数量级,从 2 ms 缩短到 200 μs。LC 空间中心的优化场重叠积分表明大多数光-物质相互作用发生在该区域。因此,这个中心区域对增加的电压的响应比整个 LC 区域更快,从而解释了在谐振时观察到的更快响应。同样,如果纳米腔内的对准得到更好的控制,则可以增强响应电压和温度的可调性。这种方法为利用更快的 LC 模式和创新的谐振纳米腔设计的超快器件铺平了道路。
更新日期:2025-01-23
中文翻译:
通过设计局部电磁场提高纳米腔中液晶的速度和可调性
向列液晶 (LC) 的速度通常受粘弹性弛豫时间的限制,粘弹性弛豫时间由粘度、弹性常数和器件厚度决定。在这里,我们通过将 LC 限制在共振纳米腔中并将电磁场设计为集中在 LC 的特定区域内来展示突破这一限制,在该区域中,分子对施加的电压产生强烈反应。将 LC 限制在 712 nm 高和 566 nm 空间的亚波长深硅 (Si) 光栅内,我们实现了导模谐振,从而在谐振波长处在 LC 空间中心产生高场限。相反,在谐振波长之外,场限制会转移到 Si 线。这种配置将谐振波长处的上升时间缩短了一个数量级,从 2 ms 缩短到 200 μs。LC 空间中心的优化场重叠积分表明大多数光-物质相互作用发生在该区域。因此,这个中心区域对增加的电压的响应比整个 LC 区域更快,从而解释了在谐振时观察到的更快响应。同样,如果纳米腔内的对准得到更好的控制,则可以增强响应电压和温度的可调性。这种方法为利用更快的 LC 模式和创新的谐振纳米腔设计的超快器件铺平了道路。