Wehaveoptimizedtheinputpulsewidthandinjectiontimetoachievethehighestpossibleoutputpulseenergyinadouble-passlaseramplifierusingtwoNd:YAGrods.Forthispurpose,wehaveextendedtheFrantz–Nodvikequationbysimultaneouslyincludingbothspontaneousemissionandpumpenergyvariation.Theeffectivepumpenergyoftheflashlampwas8.84Jforeachgainmedium.Theenergyof1Jcouldbeamplifiedtoanoutputenergyof12.17Jwiththemaximumachievedextractionefficiencyof63.18%whenaninputpulsehavingapulsewidthof168μsissent10μsaftertheabsorbedpumpenergybecomesthemaximumvalue.