Provided is a light modulator including a substrate, and a resonator configured to modulate a phase of incident light by modulating a refractive index based on an external stimulus, the resonator comprising a first reflective structure provided on the substrate, a cavity layer provided on the first reflective structure, and a second reflective structure provided on the cavity layer, wherein at least one of the first reflective structure or the second reflective structure comprises first material layers, second material layers that are alternately stacked with the first material layers, and a third material layer, and wherein each of the first material layers has a first refractive index, each of the second material layers has a second refractive index that is different from the first refractive index, and the third material layer has a third refractive index that is different from the first refractive index.