Differential gain in bulk and quantum well diode lasers

Differential gain (g/sup '/) of bulk and single-quantum-well (SQW) lasers was determined from threshold current density and differential quantum efficiency measurements. The threshold measurement technique was used to show that g/sup '/ is a function of cavity length (L) in SQW lasers and independent of L in bulk lasers. It was found that g/sup '/ of long SQW lasers (1000 mu m) is about 7*10/sup -16/ cm/sup 2/, approximately two times that of bulk lasers. At short cavity lengths (250 mu m), g/sup '/ is about the same for both laser types.<
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