Fiber Laser refers to a laser that uses rare earth-doped glass fiber as the gain medium. Fiber lasers can be developed on the basis of fiber amplifiers. High power density is easily formed in the fiber under the action of pump light, resulting in laser The laser energy level of the working substance is "population inversion", and when a positive feedback loop (to form a resonant cavity) is properly added, the laser oscillation output can be formed.
The processing requirements are becoming more and more diverse and demanding. The heart of the laser cutting machine-the laser, also has a distinction between single-mode and multi-mode. The application range of fiber laser is very wide, including laser fiber communication, laser space telecomm Water, cladding and deep welding), military and national defense security, medical equipment and equipment, large-scale infrastructure, as the pump source of other lasers, and so on.
So, what is the difference between the single-mode/multi-mold body of the laser, the heart of the laser cutting machine? This article analyzes and answers in detail, so as to prevent everyone from being blindly faced with choices in the later period.
The heart of laser cutting machine-single-mode/multi-mode analysis of laser:
As we all know, the energy distribution of the excited beam of a fiber laser is similar to the "Gaussian distribution". Today, I will take a brief look at the principle and structure of the fiber laser. First, it is composed of a pump source, a multimode coupler (combiner), and a fiber grating. , Active fiber, beam calibration output module, and passive fiber (energy output fiber). When there is only one pump module inside the laser, it is called a single-mode laser, and multiple pump modules are combined together, and multiple beams of pump light enter the active fiber through the beam combiner, so that higher power can be obtained The laser beam of this kind of multi-module combination is a multi-mode laser. Therefore, among mainstream fiber laser products, single-mode lasers are mostly small and medium power, while high-power products are mostly multi-mode lasers.
The difference between multi-mode and single-mode: single-mode has a thinner core and emits a typical Gaussian beam with very concentrated energy, similar to steep mountains, and the beam quality is better than multi-mode; multi-mode is equivalent to multiple Gaussian beams Therefore, the energy distribution is similar to an inverted cup, which is more average. Of course, the beam quality is worse than that of single mode.
According to different characteristics, the application directions of single-mode and multi-mode are also different. For example, in the cutting of stainless steel/carbon steel sheets of 1mm and below, the processing efficiency of single-mode is significantly better than that of multi-mode (single-mode is 15% faster~ 20%), and the cutting quality is similar; and in the cutting of thick plates of 2mm and above, both quality and efficiency, high-power multi-mode lasers perform better.
Used in the field of laser welding, in heat conduction welding, a single-mode laser can get a more uniform and smooth weld, so some thin materials are welded with a single-mode laser, such as the overlap welding of the tabs when the soft pack power battery is grouped; In deep penetration welding, multi-mode lasers can obtain welds with better aspect ratios, such as the welding of Bus-Bar square power battery packs.
Special attention is paid to the single-mode and multi-mode of the laser is an important basis for selecting fiber lasers. Fiber lasers are becoming more and more popular in the laser processing field due to their high electro-optical conversion efficiency, high stability, high beam quality and low cost of use. As an extremely high-quality light source, the cost has been increasing in recent years. Declining, so the traditional solid-state and gas laser markets are constantly being replaced by fiber lasers.