Liquid crystal (LC) planar optics have advanced wavefront engineering toward ultrathin designs, capturing widespread attention. However, most wavefront control in LC planar optics remains constrained to freespace due to limitations in the precision of freely controllable units. Here, LC on‐chip wavefront engineering is proposed and confirmed. By controlling the initial azimuth angle of the polarization grating, the initial phase can be engineered, as theoretically predicted by rigorous coupled‐wave analysis. Experimentally, the initial azimuth angle of a polarization volume hologram grating, used as a waveguide coupler, is ingeniously modulated using a holographic template. Consequently, several on‐chip optical elements, including lenses, vortex beam generators, and holograms, are demonstrated. Furthermore, exit pupil expansion and multiexposure technologies are adopted to enhance off‐chip functionality and enable multifunctional, highly integrated LC on‐chip photonic systems. The proposed LC on‐chip wavefront engineering may find applications in freeform optics, near‐eye displays, LIDAR, and integrated photonic systems.

中文翻译：

---

用于片上波前工程的偏振体积全息图


液晶 （LC） 平面光学器件采用先进的波前工程技术，采用超薄设计，引起了广泛关注。然而，由于可自由控制单元的精度受到限制，LC 平面光学器件中的大多数波前控制仍然受限于自由空间。在这里，提出并确认了 LC 片上波前工程。通过控制偏振光栅的初始方位角，可以设计初始相位，正如通过严格的耦合波分析理论预测的那样。在实验中，用作波导耦合器的偏振体全息图光栅的初始方位角使用全息模板巧妙地调制。因此，演示了几种片上光学元件，包括透镜、涡旋光束发生器和全息图。此外，采用出射光瞳扩展和多重曝光技术来增强片外功能，并支持多功能、高度集成的液相色谱片上光子系统。拟议的 LC 片上波前工程可能应用于自由曲面光学、近眼显示器、LIDAR 和集成光子系统。