Thesis (M.Eng.)--Chulalongkorn University, 1999

Edge emission spectra of GaAs/Al0.2Ga0.8As and In0.2Ga0.8As/GaAs single quantum well and multiple quantum well were investigated by optically-pumped technique using argon laser (5140 ํA). The structures were grown by the molecular beam epitaxial technique. Multiple quantum wells fabricated from both material systems show the possibility of stimulated emission which is the fundamental of laser action. In Al0.2Ga0.8As/GaAs case, rapid increase of edge emission from 10 multiple quantum well and 5 multiple quantum well with waveguide structures were observed when the pumping intensity reached a threshold values of~4 kW/cm2 and 2.5 kW/cm2, respectively. The spectra from In0.2Ga0.8As/GaAs 3 and 5 multiple quantum well structures showed the superlinear increase; however, the threshold pumping intensity was not clearly observed as a result of losses in the active region of these structures