We all know that laser diodes belong to photosensitive devices, so do you know how laser diodes dissipate heat? Let's take a look at it from the perspective of Xiaobian.
Why is heat dissipation so important?
When the laser diode is working, about half of the energy will become heat. Once the temperature rises, the laser wavelength will drift, the output power will be attenuated, and in severe cases, "thermal breakdown" will appear, that is, the chip will be directly burned.
What is the right way to dissipate heat?
The base material is critical.
The most commonly used is copper or copper-molybdenum alloy, and sometimes aluminum substrate is also used. Copper conducts heat well, but it is heavy, while aluminum is light, but it conducts heat slightly worse. Generally, aluminum is enough for low-power diodes, and the high-power one is best to install copper base honestly.
When we make a high-power module, the bottom plate is generally polished to the mirror surface, and then coated with thermal conductive silicone grease to ensure that the chip and the bottom plate are closely attached. This step is not sloppy.
Add thermal interface material (TIM)
Someone directly presses the chip on the heat sink, but there will be an air gap in the middle, which has a great thermal resistance. Using thermal conductive silicone grease, thermal conductive gasket or thermal grease can make the heat transfer to the radiator more smoothly.
However, the amount of attention should not be too much. If it is too thick, it will become a "thermal insulation layer". I often see that novices are too heavy in this step.
Active heat dissipation
For laser diodes that work continuously, passive heat dissipation alone is not enough. Either add a fan to blow, or use TEC (Semiconductor Refrigerator) to control the temperature.
These are the correct ways for laser diodes to dissipate heat. I believe you will have a clear understanding after reading them.