A WDDM includes a base substrate; a first mirror on the base substrate; a second mirror on said base substrate; a third mirror on the base substrate; a first optical splitter on the base substrate, wherein the first mirror is configured to reflect a first light beam to the first optical splitter, wherein the first optical splitter is configured to split the first light beam into a second light beam exiting from a first light exit surface of the first optical splitter and a third light beam reflecting to the second mirror; and a second optical splitter on the base substrate, wherein the second mirror is configured to reflect the third light beam to the second optical splitter, wherein the second optical splitter is configured to split the third light beam into a fourth light beam exiting from a second light exit surface of the second optical splitter and a fifth light beam reflecting to the third mirror.