Record Low Threshold Current Density in Quantum Dot Microdisk Laser

We demonstrate a record low threshold current density of 250 A/cm 2 in a quantum dot microdisk laser with a 31-μm diameter operating at room temperature in continuous wave regime without temperature stabilization. This low threshold current density is very close to the transparency current density estimated in broad-area edge-emitting lasers made of the same epitaxial wafer.