An optical system includes a first panel that includes a plurality of first electrodes; a second panel facing the first panel and that includes a plurality of second electrodes; and an optical conversion layer positioned between the first panel and the second panel that includes an optical conversion material. An electric field generated in the optical conversion layer by the plurality of first electrodes and the plurality of second electrodes in a multi-view mode generates a phase difference in the optical conversion layer based on a location of the optical conversion material. The plurality of second electrodes includes a plurality of sub electrodes and a common electrode, and the plurality of first electrodes and the common electrode forms a touch sensing capacitor to sense a touch in a touch mode.