Quantum dot laser diode with low threshold and low internal loss

Data are presented demonstrating that a low-threshold quantum dot laser diode can achieve very low internal optical loss. The broad-area laser diode operates at the wavelength 1.22 m and delivers 2 W of power from a 1.6 cm-long cavity with uncoated facets, with a lasing threshold current density of 10.4 A/cm². The laser diode´s internal waveguide loss is extracted from cavity length measurements to be ~0.25cm^-1. The interdependence of threshold current density and internal optical loss is discussed.