Alignment of polarization volume gratings using semi-circular arc patterns via nanofabrication technology

Polarization volume gratings have the potential for future applications such as AR due to their high single-order diffraction efficiency and large angular and wavelength response range. However, the preparation method of photo alignment, which is currently employed, presents challenges to the application of PVGs due to issues of poor uniformity and difficulty in preparing large sizes. To promote the application, a scheme for fabricating the alignment layer of PVGs by nanofabrication technology is proposed. The alignment structure, where the basic unit is a semicircular arc, was designed. We prepared the structure using EBL and spin-coated a layer of chiral liquid crystals (CLC) on top of it. The dispersion effect in white light indicates that the designed alignment structure imparts lateral periodicity to the CLC. The device could efficiently reflect specific right-polarized light and efficiently transmit specific left-polarized light. Therefore, the diffraction performance of the device can be considered to be consistent with the photo-alignment PVGs within the error allowance. This work provides what we believe to be a novel scheme for the alignment of PVGs, creating a new platform for mass production and multifunctional integrated design of PVGs.