Optoelectronic device

An optoelectronic device, comprising:

• a substrate having a top surface and a bottom surface;
• a first semiconductor stack located on the top surface and including a first semiconductor layer, a second semiconductor layer and a first active layer located between the first semiconductor layer and the second semiconductor layer, wherein the first active layer emits or absorbs a first light having a first wavelength;
• a second semiconductor stack located on the first semiconductor stack and including a third semiconductor layer, a fourth semiconductor layer and a second active layer located between the third semiconductor layer and the fourth semiconductor layer, wherein the second active layer emits or absorbs a second light which has a second wavelength smaller than the first wavelength;
• and
• a first optical structure located between the first semiconductor stack and the second semiconductor stack, and including a plurality of first parts and a plurality of second parts which are alternately arranged with a first period along a horizontal direction parallel to the top surface,
• wherein the first optical structure overlaps with the second semiconductor stack along a vertical direction.