Multi-layer patterned liquid crystal polymer thin films for spatially modulating light propagation directions and polarizations

本論文主要介紹了一種用來空間上調節光的傳播方向跟偏振態的光學薄膜結構。這種結構包含多層圖案化的雙折射薄膜,每一層都是由液晶聚合物（LCP）構成,這些聚合物的光軸方向由一層圖案化的光配向層控制而變化。這種光調制器有兩層功能層,第一層的設計是圖案化的偏振光柵,光柵向量方向可以空間上變化,已達到空間調制光的傳播方向的作用,第二層是一層圖案化的光延遲膜,可以調節出射光的偏振態。這種多薄結構的厚度小于1μm,有助于提供高分辨率的光波前結構。它還可以當做光掩模,用來產生多疇配向結構的光配向層,應用到現代液晶顯示器的制造中。為了驗證這種結構的實用性,我們成功地制作了這種多層膜結構,并用它在單次曝光的條件下制作了一個兩域光配向結構的液晶盒。這種光學薄膜結構在調制光的傳播方向跟偏振態方面有著獨特的功能,可以廣泛應用于微型制造、三維成像、光通信、光計算、光開關等等領域。In this article,an advanced optical thin film structure for spatially modulating light propagation directions and polarizations is introduced.The optical structure is composed of multi-layer patterned birefringence thin films,of which each thin film is formed by a liquid crystal(LC)polymer layer with spatially varying optical axes controlled by apatterned photoalignment layer.The optical modulator has two functional layers,where the first layer is designed as patterned polarization grating with spatially varying grating vectors to spatially steer light propagation directions,and the second layer is a patterned retardation film for controlling the output light polarizations.The overall thickness of the multi-layer films,excluding the substrate,can be less than 1μm,which offers the flexibilityto generate high resolution light wavefront structure.As a result,the optical thin film can be ideally working as a photomask for exposure on a LC photoalignment layer to generate multi-domain alignment structures,which can be applied for the manufacturing and designing of modern liquid crystal display.To verify the effectiveness of the proposed photomask,aperiodic two-domain thin film structure has been designed and fabricated and a liquid crystal cell with two-domain alignment structure has been successfully fabricated in a single exposure with the photomask.The proposed optical thin film has unique functions in modulating light propagating directions and polarizations,which has great potential to find applications on micro-fabrication,3D display,optical communication,optical computing and optical switching,etc.