CO2 vs. Fiber Laser: Which One Is Better?

Fiber Laser

Definition of fiber laser

Fiber laser refers to a laser using rare earth element doped glass fiber as gain medium.

Fiber lasers can be developed on the basis of fiber amplifiers.

Principle of fiber laser

Under the action of pump light, high power density is easy to form in the optical fiber, resulting in the “particle number inversion” of the laser energy level of the laser working material.

When the positive feedback loop (forming a resonator) is properly added, the laser oscillation output can be formed.

Applications of fiber laser

Fiber laser has a wide range of applications, including laser fiber communication, laser space long-distance communication, industrial shipbuilding, automobile manufacturing, laser engraving, laser marking, laser cutting, printing roller, metal and non-metal drilling / cutting / welding (brazing, quenching, cladding and deep welding), military and national defense security, medical instruments and equipment, and large-scale infrastructure construction, as the pump source of other lasers, etc.

Types of fiber laser

There are many kinds of classification methods for fiber lasers, among which the more common are classified by working mode, band range and dielectric doped rare earth elements.

By working mode

• Continuous fiber laser (laser cutting, welding, cladding)
• Quasi-continuous fiber laser (spot welding, seam welding, drilling)
• Pulsed fiber laser (material micromachining, scalpel, microscope, laser measurement)

By band range

• Mid infrared fiber laser (medical laser source, laser guidance)
• Green fiber laser (medical image diagnosis, holographic projection)

By doped rare earth elements

• Ytterbium-doped fiber laser (industrial processing, medical treatment, national defense)
• Erbium-doped fiber laser (laser environmental monitoring)
• Tm-doped fiber laser (laser fine cutting, laser hemostasis)

Lasers are usually named according to one or two of these three categories.

Fiber lasers have a wide range of applications. Different subdivided lasers have different characteristics and suitable application fields.

For example, the mid infrared band is safe for human eyes and can be strongly absorbed in water. It is an ideal medical laser source;

Erbium doped fiber is widely used in the field of optical fiber communication because of its suitable wavelength;

Because of its visibility, green laser is essential in entertainment and projection.

Application diagram of laser subdivision classification corresponding to relevant industries

CO₂ Laser

CO₂ laser is a kind of molecular laser. It is one of the common high-power CW lasers. The main material is carbon dioxide molecule.

The main structure of CO₂ laser includes laser tube, optical resonator, power supply and pump. The main feature is high output power and continuous operation, but the structure is complex, the volume is large and the maintenance is difficult.

Basic structure of CO₂ gas laser

Realizing particle number inversion is the key to the luminescence of carbon dioxide laser.

The working substances in the carbon dioxide laser include carbon dioxide, nitrogen and helium. After the DC power supply is input, the nitrogen molecules in the mixed gas will be excited by electron impact. When the excited nitrogen molecules collide with carbon dioxide molecules, they will transfer energy to carbon dioxide molecules, Thus, carbon dioxide molecules transition from low energy level to high energy level, forming particle number inversion and emitting laser.

① Nitrogen molecules collide with carbon dioxide molecules after excitation, so that carbon dioxide is excited separately.

② The excited carbon dioxide molecule jumps down and emits a laser

Fiber Laser vs. CO2 Laser

Optical fiber and CO2 laser have their own advantages, and different lasers should be selected according to different needs.

From the cutting technology which is widely used at present, fiber laser and CO₂ laser have their own advantages and disadvantages in the face of specific application requirements. They can not completely replace each other, but need to complement and coexist.

From the type of processing materials, due to the absorption effect, fiber lasers are not suitable for cutting non-metallic materials, while conventional CO₂ lasers are not suitable for cutting high reflectivity materials such as copper and aluminum.

In terms of cutting speed, CO₂ has advantages in sheet thickness > 6mm, while fiber laser cuts sheet faster;

Workpiece penetration is required before laser cutting, and the perforation speed of CO₂ is significantly faster than that of fiber laser;

In terms of cutting section quality, CO₂ laser is better than fiber laser as a whole

Comparison between fiber laser and carbon dioxide laser

Fiber laser has higher light conversion efficiency and lower use cost.

According to the calculation, the use cost of fiber laser is 23.4 yuan/hour, the use cost of carbon dioxide laser is 39.1 yuan/hour, of which the power cost of fiber laser is 7 yuan/hour, the water cooling cost is 8.4 yuan/hour, and other costs are 8 yuan/hour; The power cost of carbon dioxide laser is 21 yuan/hour, the water cooling cost is 12.6 yuan/hour, and other costs are 5.5 yuan/hour.

Cost comparison between fiber laser and CO₂ laser