The　comprehensive　theoretical　analyses　and　experimental　studies　on　semiconductor　disk　lasers　are　presented.　The　edge-emitting　photoluminescence　spectrum　which　reflects　the　essential　emission　properties　of　quantum　wells　is　theoretically　modeled,　and　the　result　is　in　good　agreement　with　the　experiment.　The　surface-emitting　photoluminescence　spectrum　which　carries　the　characteristics　of　the　semiconductor　microcavity　is　explained　using　the　numerically　simulated　longitudinal　confinement　factor.　The　output　characteristic　is　modeled　by　taking　into　account　the　thermal　effect,　and　the　result　is　consistent　with　the　experiment.　The　oscillating　mode　of　the　laser　is　codetermined　by　the　reflectivity　of　DBR,　the　edge-emitting,　and　the　surface-emitting　PL　spectrum.