A light wave-guide optical element for use in a head-mounted display (HMD) or in a head-up display (HUD) includes an organic optical material, an anti-reflection stack and an organic optical cover. The organic optical material includes multiple bulging tips surrounded by a periphery plane. The anti-reflection stack conformally covers the bulging tips and the periphery plane. The organic optical cover correspondingly covers the anti-reflection stack, the periphery plane and the bulging tips.