The difference between a CO₂ and fiber laser

Almost all laser cutting machines in our production halls have a fiber laser. Only a few still have a CO₂ laser. Why this distinction? We can best explain this by answering the following questions:

1. What is a CO₂ laser?

2. What is a fiber laser?

3. CO₂ laser vs. fiber laser: what’s the difference?

1. What is a CO₂ laser?

A CO₂ laser is a type of gas laser in which a powerful infrared laser beam is generated using a gas mixture. 

This happens as follows:

A tube contains a gas mixture of carbon dioxide (CO₂), nitrogen, and helium. An electric voltage generates energy in the nitrogen molecules, which transfer this energy to the CO₂ molecules. These then emit light, which is focused into a beam. This beam is directed through mirrors and a lens onto the material. Helium dissipates energy and keeps the laser stable. Thanks to the heat, it can cut through materials or engrave them. 

The laser beam has a wavelength of 10.6 µm and falls within the infrared spectrum. 

2. What is a fiber laser?

A fiber laser is a solid-state laser. A laser beam is created using an optical fiber, doped with rare earth elements such as ytterbium.

This happens as follows:

In the pump source, a laser diode generates light (not yet laser light!). This light is directed into an optical fiber cable. This fiber is doped with the rare earth element ytterbium (Yb). The ytterbium ions absorb the light and re-emit it, this time with greater intensity. Mirrors are located at the ends of the fiber, causing the light to bounce back and forth. And with each reflection, the light becomes stronger. Once the light is strong enough, it travels through a curved cable to the cutting head. The lens in the cutting head captures it, focuses it, and creates a focused laser beam.

This laser beam has a wavelength of 1.06 µm. Like a CO₂ laser, this also falls under the category of infrared light.

3. CO₂ laser versus fiber laser: what is the difference?

It is clear that the operation of a CO₂ laser differs from that of a fiber laser. This also results in a number of differences in terms of light source, wavelength, application, and efficiency. The table below illustrates this:

In the late 1970s, CO₂ lasers were the go-to method for laser cutting metal. However, these lasers require a lot of maintenance, consume a lot of energy, have a relatively low cutting speed, and struggle with highly reflective surfaces such as aluminum and copper.

With the advent of fiber lasers in the late 1990s, an alternative emerged that overcame the limitations mentioned above. Ultimately, the fiber laser established itself as a state-of-the-art technology that is now the standard for many metalworkers.

Admittedly, for thicker metals (5 mm and up) and perfectly straight lines, CO₂ lasers produce cleaner cut edges than fiber lasers. However, the advantages that fiber lasers offer in terms of accuracy, cost savings, and efficiency are usually more appealing to large manufacturing companies like 247TailorSteel.

CO₂ lasers are therefore still used for laser cutting metal. But they are primarily used for laser cutting non-metals (such as wood, acrylic, textiles, and glass). Fiber lasers are simply less suitable for this due to their short wavelength of 1.06 µm.

Questions about CO₂ and fiber lasers?

Do you have any questions about this topic? Feel free to contact us.

This article was written in collaboration with TRUMPF.
Source headerimage: TRUMPF Group