An optical phased array device may include a substrate, a light distribution unit configured to distribute input light along a plurality of paths as distributed light, a light modulator configured to modulate a phase of distributed light to establish phase-modulated light, an antenna configured to emit the phase-modulated light, a clad surrounding the light distribution unit, the light modulator, and the antenna and including a first surface facing the substrate and a second surface opposite the first surface, and a reflective layer facing the second surface of the clad. The reflective layer may be configured to reflect the phase-modulated light emitted from the antenna so that reflected light is emitted to an exterior environment that is external to the optical phased array device based on passing through the substrate.