High-Power Multimode Laser Diodes (λ = 976 nm) Based on Asymmetric Heterostructures with a Broadened Waveguide and Reduced Vertical Divergence

The effect of the active region design on the vertical far-field divergence is studied for high-power laser diodes based on asymmetric heterostructures with a 4-μm thick waveguide and active region designs based on single (SQW) and double (DQW) InGaAs quantum wells. It is shown that the number of quantum wells has a significant effect on the divergence determined by the angle with the 95% power content (Θ 95% ). For asymmetric heterostructures with an SQW active region, the beam divergence at the half-maximum level (FWHM) is 12.9°. It is experimentally shown that the transition from the SQW to the DQW design of the active region leads to an increase in the Θ 95% value from 23.2° to 41.8°. For both types of structures, the internal optical loss and internal quantum efficiency are 0.27 cm ‒1 and 99%, respectively. On the basis of asymmetric heterostructures with an active SQW region, we demonstrate high-power laser diodes emitting a CW power of 9 W at a temperature and pump current of 25°C/10 A and 55°C/11.4 A.