We present an optical device capable of displaying in two distinct viewing modes, i.e., monoview and dual-view modes. The monoview mode has a joint viewing cone and allows only the same image or video content to be displayed. The dual-view mode splits one viewing cone into two so that two different pieces of information can be displayed simultaneously in the left and the right viewing directions from the screen. Each viewing mode can be mutually switched through the modulation of the birefringence of liquid crystals. This proposed device has technical advantages of easy operation, low cost, and versatility of applications.