Body temperature reduction in high-power laser diodes using distributed waveguide design

Self-heating in laser diodes (LDs) elevates the junction temperature, degrading output power and brightness while reducing reliability by promoting catastrophic optical damage. Although advances in reducing internal losses and optimizing electrical properties have enabled longer cavity lengths, GaAs-based high-power LDs remain constrained to approximately 5-6 mm due to physical effects such as longitudinal spatial hole burning and nonlinearities. In this work, we introduce a "distributed waveguide" (DWG) design that overcomes conventional cavity-length limits. The DWG comprises alternating lasing and secondary sections, electrically isolated for separate current control yet optically coupled to ensure efficient beam transport. This configuration distributes heat more effectively, lowering the junction temperature. We fabricated GaAs-based DWG LDs in which the lasing sections operate at high currents to generate light, while the secondary sections are pumped near transparency, ensuring minimal optical loss and enhanced heat dissipation. Experimental and simulation results confirm that DWG LDs achieve significantly lower junction temperatures than standard LDs. This work provides clear evidence that innovative waveguide designs can effectively mitigate self-heating, promising enhanced performance, output power, and reliability in semiconductor lasers.