Internal optical loss and internal quantum efficiency of a high-power GaAs laser operating in the CW mode

We continue the comparative studies of high-power AlGaAs/InGaAs/GaAs semiconductor lasers with different waveguide designs. In this work, measurements were carried out for a continuous-wave mode of operation: light-current and current-voltage characteristics, threshold characteristics and their temperature dependences and crystal temperature depending on the pump current. The data obtained made it possible to reconstruct the dependences of internal optical losses and internal quantum efficiency using calculations. It was shown that the main factor affecting the power characteristics in the continuous mode of operation is the temperature stability of the laser and its relationship with internal optical losses and internal quantum efficiency. Thus, lasers based on a heterostructure with a doped GaAs waveguide with characteristic temperatures T (0) and T (1) of 120 K and 170 K, respectively, demonstrated an increase in internal optical losses to 2 cm(-1) and a drop in the quantum efficiency to 90%, which led to saturation of the output power by high pump currents. Lasers based on the heterostructure with an AlGaAs waveguide, which are characterized by higher temperature stability (T (0) = 161 K and T (1) = 280 K), had lower internal optical losses and a higher quantum efficiency. This made it possible to obtain optical power 1 W higher than that for lasers with GaAs waveguides.