A disclosed optical element includes three or more sub-wavelength convexo-concave structures having pitches less than a wavelength of an incident light incident to the optical element and having groove depths equal to each other and a periodic structure having the three or more sub-wavelength convexo- concave structures, the pitch of the periodic structure greater than the wavelength of the incident light, in which a predetermined polarization direction of the incident light is diffracted mainly into a specific order.
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