We all know that laser diodes are photosensitive devices, and many people have reported that high-power laser diodes will burn tubes, so do you know why they burn tubes? Let's take a look at it together

Laser diodes are particularly afraid of sudden changes in current, especially surge current. When the switching power supply starts or the current climbs too fast, it will impact the PN junction of the chip instantly, even if the peak value lasts only a few tens of microseconds, it will be enough for the chip to burn out due to overcurrent.

So we generally emphasize:

Current should be limited when starting, and it is better to have soft start function.

The power supply should be laser-dedicated drive, instead of ordinary DC regulated power supply.

The power-on sequence of modules must be correct: grounding first, then TEC temperature control, and then current.

The lifetime of a laser diode is strongly related to its temperature. Generally speaking, the lifetime of a chip will be shortened by half for every 10℃ increase in junction temperature. High-power LD generates a lot of heat. If the heat dissipation is not good, it is easy to "burn the tube".

Optical feedback

This is the most easily overlooked by inexperienced people.

When high-power laser is output, if it encounters a reflective surface (such as lens, metal and glass), some light will be reflected back to the end face of the chip, forming optical feedback. This reflected light will enhance the interference in the laser cavity, instantly cause local overheating, and finally burn the active region.

If you are using a high-power LD, be sure to leave a margin in driving, power supply, heat dissipation and light path.

I usually tell customers not to let the laser work in the "limit state" and leave 10% more safe space.