Thermotropic liquid crystals have recently become popular for use in optical components for augmented and virtual reality. Chiral liquid crystal (CLC), is of particular interest due to the formation of a photonic bandgap that allows for the creation of polarization-sensitive reflective optical components. Previous investigations have studied 2D diffraction gratings based on long-pitch (5 μm) CLC in combination with a 2D periodic alignment configuration. This yielded 2D diffraction patterns in transmission with the ability to switch between high and low voltage states with hysteresis. In the current study, short-pitch CLC (400 nm and 1 μm) is deposited between two substrates with perpendicularly rotating periodic photoalignment patterns, the shorter pitch resulting in a diffraction grating that produces a 2D diffraction pattern in reflection for wavelengths in the visible range. While a relatively high diffraction efficiency is achieved in the first diffraction order, additional diffraction orders with lower efficiency are present due to the complex CLC configuration in the bulk.

中文翻译：

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基于短节距手性液晶的反射式二维衍射光栅

热致液晶最近广泛用于增强现实和虚拟现实的光学元件。手性液晶（CLC）由于形成光子带隙而特别受关注，该光子带隙允许创建偏振敏感的反射光学元件。先前的研究研究了基于长节距 (5 μm) CLC 与 2D 周期性对准配置相结合的 2D 衍射光栅。这产生了传输中的 2D 衍射图案，并且能够在高电压和低电压状态之间进行滞后切换。在当前的研究中，短节距 CLC（400 nm 和 1 μm）沉积在两个具有垂直旋转周期性光对准图案的基板之间，较短的节距导致衍射光栅在可见光范围内的波长反射中产生二维衍射图案。虽然在第一衍射级中实现了相对较高的衍射效率，但由于整体中复杂的 CLC 配置，存在效率较低的附加衍射级。