Optically pumped stimulated emission (SE) and time-resolved photoluminescence (TRPL) of InGaN/(In)GaN multiple quantum wells (MQWs) grown by low-pressure metalorganic chemical vapor deposition (MOCVD) were systemically studied as a function of well and barrier thickness. The SE threshold pumping density and photoluminescence (PL) decay time were found to be strongly dependent on the well and barrier thickness. As the barrier thickness increases, the PL efficiencies and room temperature PL decay time significantly increase, which can be attributed to the improved structural quality, as seen by the reciprocal lattice mapping results. The lowest SE threshold density of 58 kW/cm 2 was obtained for the 3.0 nm well and 15.0 nm barrier sample. The experimental results indicate that the enhanced optical quality of samples with larger barrier thicknesses can be readily applied to the fabrication of InGaN/(In)GaN LDs.