Diffractive waveguide apparatus, near-eye display device, and manufacturing method for diffractive waveguide apparatus

A near-eye display device, comprising a diffractive waveguide apparatus;

• wherein the diffractive waveguide apparatus comprises:
• a waveguide substrate;
• and
• a grating structure, arranged on a surface of the waveguide substrate, and comprising a plurality of grating units;
• wherein the plurality of grating units have a first period in a first direction and a second period in a second direction, the second direction is different from the first direction;
• the first period and the second period are adjustable to cause a two-dimensional pupil expansion angle of the grating structure to be 180°;
• wherein the diffractive waveguide apparatus satisfies:
• in a field of view distribution of a normalized k-space of the grating structure, a horizontal axis is λkx/2π, a vertical axis is λky/2π;
• a radius of an inner circle is an environmental refractive index, and a radius of an outer circle is a refractive index of a waveguide substrate, the inner circle and the outer circle being concentric;
• a center field of view is located in the inner circle, fields of view with a (0,0) order diffraction and a (−1, ±1) order diffraction are located in a ring formed between the inner circle and the outer circle, and fields of view with a (0, ±1) order diffraction are located outside the outer circle to avoid the (0, ±1) order diffraction;
• a pupil expansion angle of the center field of view is 180°;
• wherein λ is a wavelength, kx is a grating vector along a x-direction in the reciprocal space, and ky is grating vector along a y-direction in the reciprocal space;
• wherein the near-eye display device comprises:
• a wearing frame, comprising two viewing window regions spaced apart from each other;
• wherein the diffractive waveguide apparatus is arranged on each of at least one of the two viewing window regions.

A manufacturing method for a diffractive waveguide apparatus, comprising:

• S1:
• providing a waveguide substrate;
• and
• S2:
• forming a grating structure on a surface of the waveguide substrate;
• wherein the grating structure comprises a plurality of grating units, the plurality of grating units have a first period in a first direction and a second period in a second direction, the second direction is different from the first direction, the first period and the second period are adjustable to cause a two-dimensional pupil expansion angle of the grating structure to be 180°;
• wherein the diffractive waveguide apparatus satisfies:
• in a field of view distribution of a normalized k-space of the grating structure, a horizontal axis is λkx/2π, a vertical axis is λky/2π;
• a radius of an inner circle is an environmental refractive index, and a radius of an outer circle is a refractive index of a waveguide substrate, the inner circle and the outer circle being concentric;
• a center field of view is located in the inner circle, fields of view with a (0,0) order diffraction and a (−1, ±1) order diffraction are located in a ring formed between the inner circle and the outer circle, and fields of view with a (0, ±1) order diffraction are located outside the outer circle to avoid the (0, ±1) order diffraction;
• a pupil expansion angle of the center field of view is 180°;
• wherein λ is a wavelength, kx is a grating vector along a x-direction in the reciprocal space, and ky is grating vector along a y-direction in the reciprocal space.