Provided are an optical modulating device and a system employing the same. The optical modulating device includes a phase modulator including a meta surface including a nanoantenna configured to couple light incident on the phase modulator, and including a quantum well layer having a multi-quantum well and configured to modulate a phase of light by modulating a refractive index according to an electrical control, and a reflective layer provided at on the phase modulator opposite to a side of the meta surface of the phase modulator and configured to resonate light coupled through the nanoantenna.