Optical structure and method for manufacturing optical structure

A method for fabricating an optical structure, comprising:

• forming a first isolation layer on a substrate layer, wherein the first isolation layer has a first opening on a side away from the substrate layer;
• forming a second isolation layer on the first isolation layer, wherein the second isolation layer has a second opening on a side away from the substrate layer, wherein a projection of the first opening on the substrate layer overlaps at least partially with a projection of the second opening on the substrate layer, and wherein a ratio of the refractive index of the first isolation layer to the refractive index of the second isolation layer is in a range of 0.95 to 1.05;
• forming, in the second isolation layer, a first conductive layer filling the second opening;
• forming a third isolation layer on the second isolation layer, wherein the third isolation layer covers a surface of the first conductive portion away from the substrate layer and has a third opening, and wherein a projection of the third opening on the substrate layer overlaps at least partially with a projection of the fourth opening on the substrate layer;
• forming a fourth isolation layer on the third isolation layer, the fourth isolation layer having a fourth opening;
• and
• forming a second conductive portion in the fourth isolation layer, wherein the fourth isolation layer is in the fourth isolation layer and fills at least the fourth opening,
• wherein a first extension direction of the first conductive portion in a plane parallel to the substrate layer differs from a second extension direction of the second conductive portion in the plane parallel to the substrate layer, and wherein a projection of the first conductive portion on the substrate layer overlaps with a projection of the second conductive portion on the substrate layer.