Diffractive optical element and device including the same

A diffractive optical element, comprising:

• a diffractive layer having one or more grating periods,
• wherein the diffractive layer comprises a plurality of optical axes which change along an in-plane rotation direction in each grating period, and the diffractive optical element satisfies Relationship 3:
• θ2×∧2>θ1×∧1 [Relationship 3]
• wherein, in Relationship 3,
• θ2 is a diffraction angle of the diffractive optical element at wavelength λ, wherein the wavelength λ is the wavelength of incident light,
• ∧2 is a grating period of the diffractive optical element,
• θ1 is a diffraction angle satisfying Relationship AA, and
• ∧1 is a grating period satisfying Relationship AA,
• θ
• 1
• =
• sin
• -
• 1
• ⁡
• (
• λ
• Λ
• 1
• )
• wherein, in Relationship AA,
• θ1 is the diffraction angle at the wavelength λ,
• ∧1 is the grating period, and
• λ is the wavelength of the incident light.