Provided in a method of fabricating an optical element array including providing a silicon substrate, providing a first element layer on the silicon substrate, the first element layer including a plurality of passive optical elements, providing a plurality of semiconductor blocks on a compound semiconductor wafer, providing semiconductor dies by dicing the compound semiconductor wafer by the plurality of semiconductor blocks, and providing a second element layer by providing the semiconductor dies on the first element layer, each of the plurality of semiconductor blocks contacting at least one corresponding passive optical element from among the plurality of passive optical elements.