Design and development of a novel miniaturized 2D electro-optic scanner based on liquid crystal for potential micro display and head-mounted display applications

In this study, we designed a miniaturized electro-optic (EO) scanner using liquid crystal (LC) as an active material capable of scanning in two dimensions. The device operates on the principle of deflection of the propagating light beam due to voltage-controlled refractive index change in the liquid crystal. The design has two stages to achieve the two-dimensional deflection. The first stage for horizontal deflection uses an offset electrode design to deflect the beam horizontally, and the second stage for vertical deflection uses LC-based diffraction grating to deflect the beam vertically. In the horizontal stage, the offset electrodes create a virtual prism is created and tuned using applied voltage to the electrodes. The change of shape of the virtual prism is due to the director's reorientation using an electric field to deflect the beam horizontally. In the vertical stage, a diffraction grating filled with liquid crystal on the top and controlled by applied voltage. The combined effect of diffraction and refraction due to the GRIN effect is achieved to deflect the beam vertically. To maximize the beam deflection, the grating height (h_gr), grating period (Λ_gr) and width (W_gr) need to be optimized. In this work, a simulation study is conducted on the proposed design to achieve 2D deflection of laser beam (λ=632 nm). The maximum horizontal and vertical deflection is 13° and 10.9° respectively. This low-cost and miniaturized can be used in augmented reality (AR), virtual reality (VR), or standalone micro-display applications.