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 µm 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 ∼0.25 cm−1. The interdependence of threshold current density and internal optical loss is discussed.