Applications and Differences of UV, Green, Fiber, and CO₂ Lasers in Laser Marking

Laser marking technology is one of the most important applications in laser processing. It uses a high-energy-density laser beam to irradiate specific areas of a material, causing vaporization or color changes that create permanent marks such as text, logos, serial numbers, and QR codes.
Laser marking can achieve character sizes from millimeters down to microns, making it especially valuable for anti-counterfeiting and product traceability.

How Laser Marking Works

The principle of laser marking is to use a focused, high-energy laser beam to melt, oxidize, or vaporize the surface layer of a material. By controlling the movement of the laser, the desired image, code, or text is engraved with high precision.

Key advantages include:

• Non-contact processing: No deformation or internal stress on the workpiece. Suitable for metal, plastic, glass, ceramics, wood, and leather.

• Durability and precision: The marks are wear-resistant and ideal for automated production.

• High flexibility: The laser beam is guided via X and Y scanning mirrors controlled by computer software, forming precise and consistent marking results.

Because the laser “tool” is simply a beam of focused light, there is no need for consumables, mechanical wear, or tool replacement. The process is fast, reliable, and cost-efficient.

Types of Lasers Used in Marking

Modern laser marking systems mainly use Fiber Lasers, CO₂ Lasers, UV Lasers, and Green Lasers. Each type has its own wavelength, mechanism, and ideal material compatibility.

1. Fiber Laser Marking

Fiber laser marking uses a rare-earth-doped fiber (usually Ytterbium) as the gain medium, typically producing a wavelength of 1064 nm in the near-infrared range.
This type of laser relies on thermal effects, heating and vaporizing the surface layer or altering its reflective properties. It can produce high-contrast, permanent marks on both metal and some non-metal materials.

Common applications include:

• Stainless steel, aluminum, brass, and titanium marking

• Tool parts, automotive components, and electronic housings

• Deep engraving and color change marking on plastics

Fiber lasers are widely used because of their low maintenance, high beam quality, and long service life.

2. CO₂ Laser Marking

CO₂ lasers are gas lasers operating mainly at 9.3 µm or 10.6 µm in the far-infrared spectrum.
They are best suited for non-metal materials, since metals have a very low absorption rate at this wavelength. The marking process uses thermal ablation, removing the surface layer to reveal a contrasting background.

Typical applications include:

• Packaging materials, leather, wood, paper, and plastic

• Food, pharmaceutical, and cosmetic labeling

• Electrical components and textiles

CO₂ lasers are ideal for organic materials and high-speed production lines, offering clear, permanent, and precise marks without consumables.

3. UV Laser Marking

UV lasers use frequency multiplication technology, converting a 1064 nm infrared laser into 355 nm (third harmonic) or 266 nm (fourth harmonic) ultraviolet light.
Because of the short wavelength and high photon energy, UV lasers can directly break molecular bonds, causing photochemical reactions rather than thermal ablation — a process known as “cold marking.”

Advantages of UV laser marking:

• Minimal heat-affected zone, preventing material damage

• Extremely fine detail suitable for micro-marking applications

• Works on metals, plastics, glass, ceramics, and coatings

UV lasers are preferred when precision and surface smoothness are critical, such as in electronics, medical devices, and semiconductor components. They produce smooth, touch-free marks with exceptional contrast.

4. Green Laser Marking

Green lasers are generated through frequency doubling of infrared light (1064 nm → 532 nm).
As visible light, green lasers offer excellent absorption for many materials that are transparent or difficult to process with infrared or CO₂ lasers.

Like UV lasers, green lasers perform cold marking through photochemical reactions, achieving high precision and minimal material removal.

They are particularly suitable for:

• Printed circuit boards (PCB)

• Glass and crystal marking

• Ceramics and polymer films

Marks produced by green lasers are fine, detailed, and have no tactile texture, making them perfect for delicate or coated surfaces.

Thermal vs. Cold Marking: A Summary

In summary:

• Fiber and CO₂ lasers rely on thermal marking, which physically removes or discolors material surfaces.

• UV and Green lasers use cold marking, altering material color through photochemical reactions with no surface damage.