Thermal crosstalk of high-power diode laser array

A three-dimensional thermal model is established for a hard solder packaged, conduction-cooled diode laser array, which contains 19 emitters, its fill factor is 30%, and the width of emitting area is 150 m. The thermal crosstalk among emitters in the diode laser array has been studied systematically. It is found that there is an obvious thermal crosstalk among the emitters in the diode laser array after the device is operated for more than 1.2 ms in continuous wave mode. While the sub-mount material changes from copper-tungsten alloy to copper-diamond composites, the thermal resistance of each emitter and the interactive thermal resistance among adjacent emitters in the diode laser array decrease obviously. It is shown that this package structure design can reduce the thermal crosstalk behavior of the emitters effectively. The effect of the emitter size and pitch on the thermal characteristics of device is analyzed while the output power of the device, the number of the emitters, the cycle of the emitters and the width of the diode laser array are kept constant. The results show that both the thermal resistance of device and the thermal resistance of each emitter decrease exponentially with the increasing of the fill factor of the diode laser array, but the thermal crosstalk characteristics among emitters are not sensitive to the emitter size and pitch. On the other hand, keeping the output power of each single emitter, the emitter size and pitch, and the width of diode laser array constant, the thermal crosstalk behavior of the emitters is heavily influenced by the number of the emitters in diode laser array. Specifically, the higher the fill factor is, the more quickly the temperature of diode laser array rises. But during the first 70 s, the highest temperature difference among these devices containing different number of emitters is about 0.5 ℃，it is benefited to the high-power output of device having high fill factor in this period. This research is significant to the design of the structure of diode laser array, especially to the optimization of the fill factor, the emitter size and pitch of diode laser arrays. More importantly, it also presents necessary references for the package structure design of diode laser array.