Color separation devices, and image sensors including the color separation devices and color filters, include at least two transparent bars that face each other with a gap therebetween. Mutually-facing surfaces of the at least two transparent bars are separated from each other by the gap such that the at least two transparent bars allow diffraction of visible light passing therebetween. The at least two transparent bars have a refractive index greater than a refractive index of a surrounding medium.