Focal tunable liquid crystal lens with floating ring electrode (Conference Presentation)

Abstract

Liquid crystal (LC) lenses have attracted much attention, owing to the light weight and an adjustable focal length without mechanically moving parts. Among the developed LC lenses, the hole-patterned LC lens has a convenient fabrication process, a simple addressing scheme, and widely tunable focal range. Nonetheless, a thick dielectric layer (TDL) has to be inserted between the hole-patterned electrode and the LC layer to distribute the fringing electric field throughout the center of the aperture hole (AH). However, the inserted TDL significantly increases the operation voltage of the LC lens. In this paper, we propose a hole-patterned LC lens with a wide diameter of 6 mm. In our design, a floating ring electrode (FRE) is embedded into the interface between the dielectric layer and the LC layer. This structure confines the electric field in the hole patterned area, therefore assists in distributing the fringing electric field throughout the LC layer and thus assists in tilting the LCs in the AH center of the lens. Therefore, the dielectric layer used in the conventional hole-patterned LC lens can be effectively decreased. The decreased thickness of the dielectric layer provides the FRE LC lens with the advantages of lower operation voltage and large tunable focal range. With a voltage of 40 V, the introduced floating ring electrode modulates the phase retardation of the LC lens in a nearly perfect quadratic form with wavefront error approaching 0.07 . The design principle, simulation and fabrication of the LC lens are demonstrated in this paper.