A　novel　coupled　multi-active-region　large　optical　cavity　structure　cascaded　by　a　tunnel　junction　is　proposed　to　solve　the　problems　of　facet　catastrophic　optical　damage　(COD)　and　the　large　vertical　divergence　caused　by　the　thin　emitting　area　in　conventional　laser　diodes.　For　a　laser　with　three　active　regions,　a　slope　efficiency　as　high　as　1.49　W/A,　a　vertical　divergence　angle　of　17.4.,　and　a　threshold　current　density　of　271　A/cm(2)　are　achieved.　By　optimizing　the　structural　parameters,　the　beam　quality　is　greatly　improved,　and　the　level　of　the　COD　power　increases　by　more　than　two　times　compared　with　that　of　the　conventional　laser.