Provided is a spatial light modulator configured to modulate light, the spatial light modulator including a first reflective layer, a resonance layer on the first reflective layer, and a second reflective layer on the resonance layer, the second reflective layer including a plurality of grating structures space apart from each other, wherein the plurality of grating structures include silicon (Si) having an extinction coefficient k that is less than or equal to 1e-5 with respect to light in the predetermined wavelength band.