Optically anisotropic, electrically tunable microlens arrays formed via single-step photopolymerization-induced phase separation in polymer/liquid-crystal composite materials

Abstract

Microlenses or arrays are key elements in many applications. However, their construction methods involve multiple fabrication processes, thereby increasing the complexity and cost of fabrication. In this study, we demonstrate an optically anisotropic, electrically tunable liquid crystal (LC) microlens array using a simple, one-step fabrication method. The microlens array is formed via photopolymerization-induced phase separation inside a polymer/LC composite. It possesses both polarization-dependent and electrically tunable focusing and imaging properties. Without applying voltage, the microlens array has a natural focal length of 8 mm, which is a result of its inherent gradient refractive index profile. Upon applying voltage above the threshold, the LC molecules reorient along the electric field direction and the focal length of the microlens array gradually increases. Based on its superior properties, the microlens array is further used for integral imaging applications, demonstrating electrically tunable central depth plane. Such LC microlens arrays could find numerous potential applications owing to their advantageous features of being flat, ultra-thin, and tunable, including 3D displays, optical interconnects, and more.

Keywords

• photopolymerization
• phase separation
• microlens array
• electro-optical properties
• integral imaging