Laser diodes based on InGaAs quantum dots (QDs) operating at 1250 nm with ultralow threshold current densities of 66 A/cm2, transparency current densities of 10 A/cm2 per quantum dot layer, and high internal quantum efficiencies of 94% have been realized using alternative precursor metal-organic chemical vapor deposition. Photoluminescence of the active QD stacks clearly indicates the requirement of varying growth parameters for subsequently deposited QD layers. The excellent performance of the QD lasers was obtained by adjusting the number of stacked QD layers to a limit given by the In content of the InGaAs strain-reducing layers grown on the QDs and individual durations of the growth interruption after deposition for each QD layer.