Abstract: A wavelength selection filter includes a first high refractive index section with a thickness T1, a second high refractive index section with a thickness T2, a high refractive index layer with a refractive index n1, a projection-depression structure layer with a refractive index n2, a filling layer with a refractive index n3, a first high refractive index section with an area ratio R1, and a second high refractive index section with an area ratio R2. With n1>n2, n1>n3, and R1+R2>1, the value of T1×{n1×R1+n2×(1?R1)} is a first parameter, the value of T2×{n1×R2+n3×(1?R2)} is a second parameter, and the ratio of the second parameter to the first parameter is 0.7 or more and 1.3 or less.

Abstract: A display is provided with a periodic structure that is dielectric and includes a support and a plurality of periodic elements. A plurality of periodic elements is arranged on a reference plane in a two-dimensional lattice form having a sub-wavelength period and are either convexities projected or concavities recessed in the reference plane. A metal layer is disposed on a surface of the periodic structure. The surface corresponds to a plane including a region of the reference plane surrounding the individual periodic elements and surfaces of the periodic elements. The metal layer's profile conforms to a surface profile of the periodic structure. The plurality of periodic elements have an interval therebetween in a first direction in which the plurality of periodic elements are arranged in a two-dimensional lattice form. The interval is different from an interval between the periodic elements in a second direction intersecting the first direction.

Abstract: An optical device includes a concave-convex structure layer having a concavo-convex structure on a surface thereof, the concavo-convex structure formed of a plurality of convexities or a plurality of concavities which are arranged with a sub-wavelength period, a high refractive index layer made of a material having a refractive index higher than that of the concavo-convex structure layer and located on the concavo-convex structure while having a surface conforming to the concavo-convex structure, and a low refractive index layer made of a material having a refractive index lower than that of the high refractive index layer and located on the high refractive index layer. The high refractive layer includes first grating high refractive index portions located at a bottom of the concavo-convex structure to form a first sub-wavelength grating, and second grating high refractive index portions located at a top of the concavo-convex structure to form a second sub-wavelength grating.

Abstract: An optical device including a concavo-convex structure layer composed of a plurality of protrusions arranged having a subwavelength period; a high refractive index layer located on the concavo-convex structure and having a surface shape following the concavo-convex structure; and a low refractive index layer located on the high refractive index layer and having a surface shape following a concavo-convex structure on a surface of the high refractive index layer. The high refractive index layer includes a first grating high refractive index region located on a bottom of the concavo-convex structure to form a subwavelength grating, and a second grating high refractive index region located on a top of the concavo-convex structure to form a subwavelength grating. The high refractive index layer has a refractive index higher than both the refractive indices of the concavo-convex structure layer and the low refractive index layer.

Abstract: A wavelength selection filter includes a first high refractive index section with a thickness T1, a second high refractive index section with a thickness T2, a high refractive index layer with a refractive index n1, a projection-depression structure layer with a refractive index n2, a filling layer with a refractive index n3, a first high refractive index section with an area ratio R1, and a second high refractive index section with an area ratio R2. With n1>n2, n1>n3, and R1+R2>1, the value of T1×{n1×R1+n2×(1?R1)} is a first parameter, the value of T2×{n1×R2+n3×(1?R2)} is a second parameter, and the ratio of the second parameter to the first parameter is 0.7 or more and 1.3 or less.

Abstract: A display is provided with a periodic structure that is dielectric and includes a support and a plurality of periodic elements. A plurality of periodic elements is arranged on a reference plane in a two-dimensional lattice form having a sub-wavelength period and are either convexities projected or concavities recessed in the reference plane. A metal layer is disposed on a surface of the periodic structure. The surface corresponds to a plane including a region of the reference plane surrounding the individual periodic elements and surfaces of the periodic elements. The metal layer's profile conforms to a surface profile of the periodic structure. The plurality of periodic elements have an interval therebetween in a first direction in which the plurality of periodic elements are arranged in a two-dimensional lattice form. The interval is different from an interval between the periodic elements in a second direction intersecting the first direction.