Reflowable liquid crystal geometric phase element for vertical cavity surface emitting laser projector

Abstract

We proposed a reflowable liquid crystal (LC) geometric phase element for vertical cavity surface emitting laser (VCSEL) projector. By photo alignment technology and LC one drop fill process, we realized an active LC geometric phase element and pattern switchable VCSEL projector. According to geometric phase distribution, the incident light was transformed into different light distribution, such as flood pattern, beam multiplication, or wider illumination. When voltage was applied, all LC directors aligned perpendicularly to substrates and the geometric phase distribution vanished. Therefore, the output light remained as the original projecting pattern. Due to narrow wavelength range of the VCSEL, the optical performance, such as diffraction efficiency and phase difference, was not decayed by the dispersion of geometric phase. We made a record of 3 × 3 mm LC cell with our in-house ink-jet printing system. The transmittance was over 95%, and the switching time was <5 ms.