Liquid-crystal-based diffractive optical elements with high Pancharatnam-Berry phase accuracy for holographic displays fabricated using an optimized liquid crystal on silicon device.

A rapid and accurate photoalignment technique was proposed for the fabrication of liquid crystal Pancharatnam-Berry phase diffractive optical elements (LC PB-DOEs). The in-plane orientation of LCs was precisely manipulated through the polarized illumination of an optimized liquid crystal on silicon (LCOS) device. LCOS and thereafter spatial light modulator (SLM) can generate polarization patterns at pixel level at will. The quality of such alignment was improved significantly by minimizing the phase flicker of the phase-only LCOS SLM. This was confirmed by the increase of the measured quality of the holographic images reconstructed using our DOE in terms of structural similarity (SSIM) and peak signal-to-noise ratio (PSNR) at 30% and 5%, respectively. Furthermore, a bi-focal LC PB-lens was fabricated and used as a high quality Fourier lens in holographic display to validate the usefulness of such LC PB-DOEs. This work illustrated a ubiquitous approach of fabricating different types of lightweight and thin form factor DOEs of random phase patterns at pixel level with low cost and high throughput.