We all know that laser diodes are widely used in daily life, so do you know how to dissipate heat? Let me talk to you briefly.

The heat dissipation problem of laser diode actually started from the packaging layer. Generally, when the chip is working, some of the electric energy will be converted into light energy, and the rest will become heat. If this heat can't get out, it will make the junction temperature soar. If the temperature is higher, the output power will drop, the spectrum will drift, and even the PN junction inside the chip will be broken down seriously.

So when we make a laser product, we should first look at what package it is, such as TO tube, C-mount, or optical fiber coupling module. Like TO package, low-power laser diodes usually rely on metal shell to conduct heat, and an aluminum base can make do. But if you are doing medium and high power, you can't be so "make do". Radiator and thermoelectric cooler (TEC) are all needed.

Now, in order to simplify the design, some manufacturers will directly use the package with integrated heat dissipation base, such as the one with diamond substrate or ceramic substrate, which has good thermal conductivity, but the price is not cheap. For ordinary low-power laser diodes, the heat dissipation effect can also be stable with a thicker copper plate and good thermal conductivity silicone grease.

Sometimes it is easy to overlook the relationship between heat and optical system. Temperature changes will cause wavelength drift and affect the collimation effect. For example, for the red light positioning module, sometimes customers complain that the brightness is flickering, but in fact, the heat has not dissipated, the wavelength has drifted, and the focus of the optical lens is off. To solve this kind of problem, in addition to the design of heat dissipation structure, constant current drive and temperature control feedback are also key.

Therefore, the heat dissipation of laser diode can not be solved by a heat sink alone, it is a part of the whole system design. From packaging to installation mode, from material selection to driving circuit, it is interlocking. If you really want to make the laser tube run stably for a long time, you have to look at the whole heat conduction path from the heat source.