We report small-signal modulation bandwidth and differential gain measurements of a single-layer self-organizedIn0.4Ga0.6As/GaAsquantum dot laser grown by molecular beam epitaxy. The 3 dB bandwidth of single-mode ridge waveguide lasers was measured to be 7.5 GHz at 100 mA under pulsed measurements, demonstrating the possibility of high speed operation of these devices. The differential gain was measured to be1.7×10−14 cm2.©1997 American Institute of Physics.