Sputtered SiOxNy thin films: improving optical efficiency of liquid crystal diffuser elements in multi-focal near-to-eye display architecture

In this work we present reactive sputtered SiOxNy films with a variable refractive index as a convienent solution for contrast improvement of liquid crystal diffuser multi stacks in near-to-eye AR/VR displays. The focus concerns minimization of light reflections between internal structures, in particular ITO, by optimizing internal layers through tailored properties of thin film coatings, as well as subsequent laser patterning of thin film stack. Inorganic thin films have been deposited on glass by physical vapor deposition. Corresponding refractive index, thickness, uniformity and dielectric characteristics and other electro-optical properties have been measured and their impact on the resulting optical performance of the final integrated element stack has been compared against counterparts utilizing traditional polyimide and SiOx films.