In　order　to　solve　the　contradiction　between　large　optical　cavity　(LOC)　and　low　threshold　current,　a　new　semiconductor　laser　which　has　three　quantum　wells　with　higher　barrier　and　asymmetric　broad　waveguide　structure　is　designed.　The　laser　can　sustain　low　threshold　current　with　large　optical　cavity.　GaAs/AlGaAs　three　quantum　wells　and　3.6　μm　super　large　optical　cavity　waveguide　are　grown　by　metal　organic　chemical　vapor　deposition　(MOCVD).　The　980　nm　semiconductor　laser　is　fabricated.　As　a　result,　the　threshold　current　of　4　mm　LOC　semiconductor　laser　is　1105.5　mA　and　the　vertical　divergence　angle　is　15.6°.　An　output　power　of　15.9　W　is　reached　with　injection　current　of　25　A.　The　results　show　that　the　designed　structure　is　effective　for　light　field　expanding,　which　can　realize　large　optical　cavity　and　guarantee　low　threshold　current.　©　2016,　Chinese　Lasers　Press.　All　right　reserved.