In this study, a high-power diode laser bar assembly is developed with good heat dissipation in long pulse operation mode. The thermal behavior and stress distribution are investigated in order to characterize the cooling capability and reliability. The optimal thermal resistance reaches 0.81K/W for each bar, based on the custom designed cooling plate, which is 0.6K/W lower than conventional coolers. The maximum thermal stress of laser bar is 39.4MPa under the working condition, which is less than half of the stress for previous conventional diode laser. Reliability of the device is improved as the diode laser works in a low stress status with long pulse width mode. The light power of the diode laser achieves 120W/bar with pulse duration of 30ms in 10Hz, and 200W/bar with 10ms, 10Hz, respectively. The diode laser of lifetime test passed 4.5×107 shots under the condition of 30ms, 10Hz@120A.
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