An athermal optical modulator includes a waveguide, a ring resonator configured to receive light input from the waveguide and output modulated light to the waveguide, the ring resonator including a ridge unit located at a center of the ring resonator in a vertical section, a first contact connected to one side of the ridge unit and a second contact connected to the other side of the ridge unit, the first contact and the second contact forming paths for applying electricity to the ring resonator to form an electric field in the ring resonator, and a polymer layer covering the ridge unit.