Using solid source molecular beam epitaxy, quantum dot lasers with a single active layer have been fabricated, The influence of the waveguide design on basic device properties has been investigated. Through the use of a large vertical cavity a significant reduction in threshold current density could be achieved. Slope efficiencies of more than 1 W/A and absorption levels as low as 2.6cm(-1) could be realized. First high power devices with wall-plug efficiencies of up to 50% were fabricated, demonstrating the high quality of these quantum dot lasers,