Jau Hung-Chang, Lin Yi-Ting, Li Cheng-Chang, Chen Chun-Wei, Lin Tsung-Hsien
Opt Express. 2019 Apr 15;27(8):10580-10585. doi: 10.1364/OE.27.010580.
We propose an optically rewritable dynamic phase grating based on polymer-templated azo liquid crystal in a blue-phase structure. The grating consists of alternating blue-phase and light-induced isotropic-phase regions, patterned by ultraviolet illumination. In the field-off state, the grating is hidden (showing no diffraction), due to index matching between the two phases. An index change is induced in the blue-phase regions when an external voltage is applied, while the refractive index of the isotropic-phase regions remains the same. The resulting periodic index modulation causes the grating to diffract light. The diffraction efficiency is independent of incident polarization, and the electro-optic response is in the sub-millisecond scale. Enabled by the reversible photoisomerism of the azobenzene, we demonstrate optical-patterning, -erasure, and re-patterning of a single liquid-crystal cell into different grating geometries.
我们提出了一种基于聚合物模板偶氮液晶蓝相结构的光学可重写动态相位光栅。该光栅由交替的蓝相和光致各向同性相区域组成，通过紫外光照进行图案化。在无电场状态下，由于两相之间的折射率匹配，光栅是隐藏的（不显示衍射）。施加外部电压时，蓝相区域会引起折射率变化，而各向同性相区域的折射率保持不变。由此产生的周期性折射率调制使光栅能够衍射光。衍射效率与入射偏振无关，电光响应在亚毫秒尺度。基于偶氮苯的可逆光异构化，我们展示了将单个液晶盒进行光学图案化、擦除以及重新图案化为不同光栅几何形状的过程。
