Before deciding on power, configuration, or portable vs fixed (covered in our portable vs workstation guide), there's a more fundamental decision: wavelength. Fiber, CO₂, and UV lasers aren't simply different power tiers of the same tool — each interacts with materials differently, and choosing wrong often produces no usable result at all.
Why Wavelength Determines What a Laser Can Actually Mark
How strongly a material absorbs a given wavelength varies enormously by composition. A wavelength that couples efficiently into metal can pass largely through clear glass or barely affect certain plastics.
Fiber Lasers — The Metal Workhorse
Fiber lasers operate in the near-infrared range and are the standard choice for marking metals — stainless steel, aluminium, titanium, brass — along with many engineering plastics, through surface ablation, annealing, or engraving. They dominate industrial part marking precisely because metals generally absorb near-infrared light efficiently.
CO₂ Lasers — The Non-Metal Specialist
CO₂ lasers operate at a much longer wavelength, poorly absorbed by most metals but coupling efficiently into organic and non-metallic materials — wood, leather, paper, most plastics, glass, and ceramics. This is the inverse of fiber's strength: a CO₂ laser generally isn't suitable for bare metal, while fiber generally isn't the right choice for wood or leather.
UV Lasers — Cold Marking for Sensitive Materials
UV lasers operate at a much shorter wavelength, making UV marking a "cold" process with minimal heat generation compared to fiber or CO₂. This matters for heat-sensitive materials — glass, transparent polymers, PCBs — where thermal stress would crack or deform the substrate. The trade-off is typically lower power, generally fine since UV applications prioritise precision over speed.
Choosing by Material — A Practical Reference
| Material | Best wavelength |
|---|---|
| Stainless steel, aluminium, titanium, metal alloys | Fiber |
| Wood, leather, paper, cardboard | CO₂ |
| Glass, ceramics (general) | CO₂ |
| Glass, transparent polymers (heat-sensitive) | UV |
| PCBs, fine electronics | UV |
When a Single Wavelength Isn't Enough
Operations marking a genuinely mixed range of substrates may find no single laser type covers the full product range well. The practical answer is usually maintaining two systems, or accepting some jobs need outsourcing rather than forcing an unsuitable wavelength onto a material.
A Note on Power and Configuration
Wavelength selection answers whether a laser type will work on a material at all; power and configuration answer how well it performs once the right wavelength is established — see our traceability marking guide for marking depth considerations.