Progress in industrialization of domestic kilowatt-level continuous optical fiber green light

April 10, 2024

01: New energy application development

Due to its short-wavelength working characteristics, green lasers have important applications in laser precision processing, laser display, biomedicine, microelectronics, information storage, optical measurement and other fields. In the field of industrial processing, since different materials have different absorption rates for lasers in different wavelength bands, the overall trend is that the shorter the wavelength of the laser, the greater the photon energy, and the higher the absorption of high-reflective metal materials. Copper is the third most used metal in the world after iron and aluminum. It is widely used in many high-end industrial fields, such as new energy vehicles, aerospace, high-speed trains, intelligent terminal products, and electronic communications. The 1 micron band infrared fiber laser currently used on a large scale has weak absorption of copper, and the absorption rate changes drastically with temperature (4%–17%). There are large spatters, pores, and cracks in the processing of copper materials. , large thermal impacts, uncontrollable penetration and other shortcomings. The above problems have a great negative impact on various application fields of copper materials. For example, in the processing of new energy vehicle power batteries, spatter will not only affect the welding efficiency of copper materials but also affect the production safety, performance and life of the battery. .
At room temperature, copper's absorption rate of near-infrared wavelengths (about 1 μm) is less than 5%, which is equivalent to 95% of laser light being reflected. The absorption rate of copper for green light wavelength (515nm or 532nm) exceeds 40%, which is nearly an order of magnitude higher than that of the near-infrared band. Compared with the common 1-micron band near-infrared laser, the short wavelength of the green laser naturally has a lower beam divergence angle and a smaller focused spot, so it has more advantages in processing. In particular, green fiber lasers based on the currently booming high-power fiber laser technology will have broad application prospects due to their high average power, good beam quality, strong stability and many other advantages. The international situation is constantly changing, and regional conflicts between major powers are frequent, which has created many uncertainties in the global economy. The domestic economic operation is generally stable, and the growth rate has slowed down, resulting in less demand for new production capacity. As the rapid development of the new energy industry enters a new stage, the demand for high-quality, high-stability, and high-efficiency welding light sources is rising rapidly. Domestic kilowatt-class ultra-high-power green lasers have greatly improved my country's new energy industry. It is of great significance to reduce costs efficiently and develop rapidly. ​


Current status of research on a 2-watt continuous green light

In recent years, commercial green light lasers have made great progress. The German TRUMPF Company and the American IPG Company have obtained ultra-high-power green light output of more than 3 kW and 1 kW through disc laser technology and fiber laser technology, respectively.


Currently, only Shenzhen OUDA Laser can supply high-power continuous fiber green light lasers in batches in China. In June 2022, OUHK Laser took the lead in launching a 500W single-mode green laser that can be used for highly reflective metal processing. This laser has been used in batches in power battery manufacturing, welding applications and 3D printing. In July of the same year, OUHK Laser completed a kilowatt continuous green light prototype. In September 2023, the 1000W single-mode continuous green light laser, which has been polished for more than a year, was officially launched on the market. At the same time, the fiber-coupled output 1000W/2000W/3000W multi-mode fiber green light laser was launched for welding of highly reflective materials. Provide more professional solutions.
03Gongda Laser 1000W single-mode continuous green light emitter

Partial data of 1000W single-mode continuous green light test of OUHK Laser PN: GCL-1000-F-S-W
04 OUHK Laser 3000W multi-mode continuous green light

Partial data of OUHK Laser 3000W multi-mode continuous green light test Product PN: GCL-3000-B-I-W
Typical welding application progress

High-power kilowatt continuous green light can currently be used in power battery welding for new energy vehicles. The main welding materials for lithium batteries are copper and lithium, which can be mainly divided into several types of welding, such as copper-copper, copper-aluminum, and aluminum-aluminum. For these welding needs, infrared lasers are currently mainly used. Since the absorption rate of copper and aluminum materials for infrared wavelengths is low, generally 2%–5% at room temperature, the absorption efficiency is low and the absorption is unstable, resulting in an unstable welding pool that is prone to large spatter, pores, cracks, and A relatively large heat-affected zone will be formed, resulting in low welding effect and yield, which is a pain point in current lithium battery welding. Although infrared lasers have been optimized many times, the emergence of especially ring-shaped spot continuous high-power lasers, coupled with process steps such as nickel and zinc plating on the surface of welding materials, have alleviated some welding problems of highly reflective materials to a certain extent. In the welding of multi-layer lugs and copper in lithium batteries, as well as the welding of dissimilar metal materials between copper and aluminum, infrared lasers are currently used for welding, and the yield rate is low. Feedback from terminals shows that for future mainstream 46 series large cylindrical batteries, infrared laser welding will be used for full tab welding, and the yield rate on the test line is less than 80%; if high-power green laser is used for welding, the yield rate can reach 95% %above. In order to obtain higher welding efficiency and better welding effects, OUDA Laser launched a high-power continuous green light of 1000-3000W, which was officially delivered to the market around September this year.

Some high-power green light welding cases are shown below: (1) Large cylindrical battery negative electrode current collecting plate welding, welding method: copper-copper foil stack welding; welding material: 0.2mm copper and 30 layers of 6 mm copper foil;
(2) Copper-aluminum welding: cap pole welding, welding method: copper-aluminum tailor welding; welding material: copper cap and aluminum pole:

(3) Square case battery pole adapter piece welding, welding method: copper-copper tailor welding, welding material: 1mm thick copper:
(4) Welding of multi-layer tabs and square case battery poles, welding method: aluminum foil-aluminum stack welding, welding materials: 50 layers of positive tabs (ultrasonic pre-welding) and square case battery positive posts (3 mm):


(5) Welding multi-layer tabs and square case battery poles, welding method: copper foil-copper stack welding, welding materials: 50 layers of negative tabs (ultrasonic pre-welding) and 3mm square case battery negative poles. The welding results are as follows:

06Green laser 3D printing

On June 28, 2023, at the Additive Manufacturing Industry Development (Guangzhou) Forum and the 2023 Additive Manufacturing Industry Annual Conference, Zuo Shiquan, chief engineer of the Equipment Industry Development Center of the Ministry of Industry and Information Technology, said that the core hub of the modern industrial system The commanding heights are the industrial mother machines, which are divided into additive manufacturing, subtractive manufacturing and equal material manufacturing. As a key development direction and field of industrial machinery, additive manufacturing is also a key field and direction of our manufacturing power. Accelerating the development of additive manufacturing is an important foundation for promoting the development of high-end, intelligent, and green manufacturing. The scale of the additive manufacturing industry is expected to exceed 100 billion in the next five years. Based on current estimates, if the average annual growth rate is 25%, it will probably reach 100 billion by 2027. Several folding screen flagship mobile phones released in 2023, as well as consumer electronics leader Apple, have begun to use 3D printing equipment for precision parts processing, marking the beginning of metal 3D printing equipment entering the equipment supply chain of the trillion-dollar consumer electronics market. As the scope of metal 3D printing continues to expand, application scenarios increase, and unit costs gradually decrease, the future space for metal 3D printing equipment is huge. Germany's TRUMPF is currently the only manufacturer in the world to launch high-power green laser metal 3D printing equipment, using TRUMPF's high-power disc continuous green light laser. However, due to the high price of lasers and equipment, application promotion has been slow. IPG's high-power QCW kilowatt fiber green light laser can be used as a light source for 3D printing of highly reflective metal materials. OUHK Laser has become the third manufacturer in the world to launch high-power green light lasers. It will launch 500W single-mode continuous green light in 2022. In September 2023, it will launch single-mode and multi-mode kilowatt continuous green light lasers for highly reflective materials (pure Green light 3D printing of copper, copper alloy, aluminum alloy, etc.) and precious metals (gold, silver). Green laser 3D printing equipment can cover almost all 3D printing needs of commonly used metal materials, including all types of materials for infrared metal 3D printing equipment. Especially for 3D printing of pure copper materials, we have conducted a lot of verification and testing. At present, the density of 3D printed samples of pure copper materials can reach more than 99.5%, and the material parameters of the printed samples are mechanical strength, thermal conductivity, and electrical conductivity. Basically equivalent to die casting samples.