Waveguide display using polymer-dispersed liquid crystal

Abstract

In this paper, we demonstrated two types of novel displays: light waveguide display and arrayed waveguide display. In the light waveguide display, light emitted from commercial LEDs propagates in a glass planar waveguide with a polymer dispersed liquid crystal (PDLC) upper layer. When the voltage is off, light would be partially scattered via PDLC and that pixel becomes bright and opaque. When the voltage is on, PDLC is properly aligned so that light would not be scattered, showing a transparent pixel. By electrically controlling the PDLC, a counting seven-segment pattern is clearly displayed. Arrayed waveguide display had been theoretically proposed to be a full color display with high light-use efficiency. Light of three primary colors from an emitter array could be coupled into a waveguide array upon which is the PDLC switches. In our design, the core of the waveguide is made of SU-8 photoresist while the side and under cladding is polymethyl methacrylate (PMMA). The upper cladding PDLC is controlled pixel by pixel so that the light can be selectively scattered. Both displays were carefully patterned and packaged with their driving circuits. Furthermore, since most materials are transparent and low weight, the displays are applicable for see-through headmounted displays.