808 nm laser diode with a stepped-structure heat sink for high-efficiency laser wireless power transmission

As the output power of laser diodes increases, the resulting thermal load leads to elevated chip temperatures and reduced electro-optical conversion efficiency. To address this challenge, we design a stepped-structure heat sink integrated with multi-channel water cooling in which 15 laser diode chips are arranged in a stepped configuration to achieve efficient thermal management. Experimental results show that the output power of a stepped heat-sink module increases with driving current, accompanied by a center-wavelength redshift of 3.82 nm. The module delivers 138.5 W with a peak electro-optical conversion efficiency of 65.07%, while the maximum device temperature is maintained at approximately 28.6°C under steady-state operation at 8 A. Furthermore, 4 such modules are spectrally beam-combined along the fast axis and coupled into a 200 μm/0.22 NA optical fiber, achieving 422.6 W continuous output power with a maximum efficiency of 59.43% at 6.91 A. These results demonstrate an effective thermal management solution for high-power laser wireless power transmission.