Ananalysissolutionofrateequationisderivedforverticalcavitysurface-emittinglasers.BasedontheenhancedspontaneousemissioncausedbyVCSELsandinfluenceofnonradiativerecombination,therelationbetweenoutputpropertiesandstructuralparametersofmulti-quantumwells(MQWs)isobtanined.Itwasfoundthatthecharacteristiccurveofa"thresholdless"laserisstronglynonradiativedepopulation-dependent.Whenthenonradiativedepopulationisnozero,thelight-currentcharacteristicisnotlinearlyevenforanidealclosedmicrocavity.Thelightoutputisincreasedbytheenhancedwellnumberandbythereducedwidth.Inparticular,alowerthresholdcurrentdensityforMQWsstructureintheshortcavityisrealizedbyus,meanwhilethesharpnessofthevariationdependsonspontaneousemissionfactor.
