When setting up a fiber laser engraver, three of the most important parameters are power, speed, and frequency. These settings directly affect engraving depth, marking darkness, surface finish, and processing efficiency.

For MOPA fiber lasers, there is one more important parameter to understand: pulse width. By adjusting pulse width, you can further control how the laser interacts with different materials.

In this guide, we explain how laser engraving power, speed, frequency, and MOPA pulse width work, how they interact, and how to adjust them for common engraving applications.

1. What Do Power, Speed, and Frequency Mean in Laser Engraving?

• Power: The laser output level, usually expressed as a percentage.
• Speed: The scanning speed of the galvanometer, usually measured in mm/s.
• Frequency: The number of laser pulses emitted per second, usually measured in kHz.

2. Laser Power: How It Affects Engraving Results

Laser power controls the amount of laser energy delivered during processing and strongly affects engraving depth, marking darkness, and the amount of material removed.

What Happens When You Increase Laser Power?

• More energy is delivered to the material.
• Engraving becomes deeper and darker.
• Material removal and ablation become stronger.
• Metal surfaces can become darker more easily.
• Too much power may cause overburning, bubbling, scorching, or workpiece deformation.

What Happens When You Reduce Laser Power?

• Less energy is applied to the material.
• Engraving becomes shallower and lighter.
• Lines may become thinner and more suitable for light marking.
• If power is too low, the mark may become faint or may not appear clearly.

Important: Higher power is not always better. Excessive power can damage the material surface and may cause burrs, burnt edges, or unwanted thermal effects.

Suggested image position: Power comparison test, 10%–100%

Image Alt Text: Fiber laser engraving power comparison from 10 to 100 percent

3. Laser Engraving Speed: Controlling Energy Exposure

Laser engraving speed determines how quickly the laser beam moves across the workpiece.

The faster the laser moves, the less time it stays on each area. The slower it moves, the longer the exposure time and the higher the accumulated energy.

What Happens When You Increase Speed?

• The laser spends less time on the material.
• Total energy input per area decreases.
• The engraving becomes lighter and shallower.
• Higher speeds are useful for fast marking and light engraving.
• If the speed is too high, lines may become faint, incomplete, or discontinuous.

What Happens When You Reduce Speed?

• The laser remains on the material for longer.
• Accumulated energy increases.
• The mark becomes darker and deeper.
• If the speed is too low, the material may overheat, blacken, carbonize, or develop blurred edges.

Key relationship: Power and speed work together. If power is increased, speed can usually be increased accordingly. If power is reduced, speed may also need to be reduced to maintain a similar marking effect.

Suggested image position: Speed comparison test, 100–1000 mm/s

Image Alt Text: Fiber laser engraving speed comparison from 100 to 1000 mm per second

4. Laser Frequency: Pulse Density and Surface Finish

Laser frequency refers to the number of laser pulses emitted per second. It affects pulse overlap, line smoothness, engraving texture, and marking appearance.

Higher Frequency

• More pulses are emitted within the same period.
• Pulse spacing becomes denser.
• Spot overlap increases.
• Lines generally appear smoother and finer.
• Suitable for fine marking and grayscale images.

Lower Frequency

• Pulses are more widely spaced.
• Spot overlap decreases.
• The marking texture becomes more noticeable.
• Suitable for applications where deeper engraving is required.

Frequency Settings for Metals

For materials such as stainless steel and aluminum:

• Higher frequency: Produces finer lines and more uniform surface processing, suitable for dark marking and detailed logos.
• Lower frequency: Concentrates pulse action and can be useful for deeper engraving, although the surface may appear more textured.

Frequency Settings for Plastic, Wood, and Acrylic

• Very high frequency may increase heat accumulation and cause burning or carbonization.
• Reducing frequency appropriately can help reduce excessive heat buildup.

Important: Frequency controls pulse density rather than simply acting as another power setting. Under the same average power conditions, increasing the frequency means the energy is distributed across more pulses.

Suggested image position: Frequency comparison test, 1–10 kHz

Image Alt Text: Fiber laser marking frequency comparison showing different pulse densities

5. How Power, Speed, and Frequency Work Together

The best fiber laser settings are usually found by adjusting power, speed, and frequency together rather than changing only one parameter.

For Deeper and Darker Engraving

• Increase power.
• Reduce speed.
• Adjust frequency as needed to maintain a finer marking surface.

For Light, Detailed, or Grayscale Marking

• Reduce power.
• Use a lower or moderate speed.
• Increase frequency to improve spot overlap and detail.

For Fast Batch Marking

• Increase speed.
• Increase power accordingly.
• Use a moderate frequency.

6. Common Fiber Laser Setting Mistakes

Mistake 1: Increasing Power Without Adjusting Speed

Using excessive power while keeping speed too low may burn the workpiece and create burnt edges.

Mistake 2: Adjusting Only Speed

If the speed is too high, the laser may not leave a clear mark. If the speed is too low, the material may overheat.

Mistake 3: Changing Frequency Without Considering the Material

An unsuitable frequency may lead to excessive burning on some plastics or a coarse marking texture on metals.

Simple rule:
Power controls engraving intensity.
Speed controls exposure time.
Frequency controls pulse density.

7. Fiber Laser Settings Reference Table

The following settings are starting-point references for fiber laser marking. Actual parameters should be adjusted according to the material, focus, lens size, and desired result.

Application	Power	Speed	Frequency
Black marking on stainless steel	60–80%	100–300 mm/s	40–80 kHz
Light logo marking on metal	30–50%	300–800 mm/s	30–60 kHz
Deep engraving	70–90%	50–150 mm/s	20–40 kHz
Plastic marking	20–40%	200–500 mm/s	20–40 kHz
Grayscale photo marking	40–60%	200–400 mm/s	60–100 kHz

Note: These settings are for reference only. Actual results depend on material composition, focus, lens size, machine configuration, and other processing conditions.

8. MOPA Pulse Width: An Advanced Laser Setting

Standard Q-switched fiber lasers normally use a fixed pulse width. MOPA fiber lasers, however, allow the pulse width to be adjusted.

Pulse width describes how long each laser pulse lasts and is usually measured in nanoseconds, or ns.

What Does MOPA Pulse Width Control?

Pulse width changes how the laser energy interacts with the material.

• Short pulse width: Shorter laser-material interaction time, smaller heat-affected zone, less melting, and cleaner edges.
• Long pulse width: Longer heating time, stronger thermal effect, more melting, oxidation, and material heating.

9. Short, Medium, and Long MOPA Pulse Width

Short Pulse Width: About 2–6 ns

• Very short laser-material interaction time.
• Less heat spreads into the surrounding material.
• Produces clean edges and fewer burrs.
• Suitable for fine marking on stainless steel, anodized aluminum, grayscale images, thin parts, and heat-sensitive workpieces.
• Deep engraving efficiency may be lower.

Medium Pulse Width: About 8–20 ns

• Balances impact and thermal effects.
• Provides some engraving depth without excessive edge burning.
• Suitable for general logos, characters, and common metal marking applications.

Long Pulse Width: About 30–200 ns

• Produces a stronger thermal effect.
• More heat is transferred into the material.
• Can create deeper material removal.
• Edges may develop burrs, discoloration, melting, or thermal deformation.
• Suitable for deeper metal engraving, coating removal, and heavier material processing.

10. Frequency vs. Pulse Width: What Is the Difference?

• Frequency (kHz): How many pulses are emitted per second.
• Pulse width (ns): How long each individual pulse lasts.

A simple way to understand the difference is:

• A laser pulse is like one shot.
• Frequency is how many shots occur per second.
• Pulse width is how long each individual shot lasts.

11. MOPA Pulse Width Test Example

For a simple comparison test, keep power, speed, frequency, and focus unchanged and adjust only the pulse width.

Example setup for a 30W MOPA fiber laser:

• Power: 50%
• Speed: 200 mm/s
• Frequency: 50 kHz
• Pulse widths: 4 ns, 10 ns, 30 ns, and 80 ns

Expected Visual Differences

• 4 ns: Fine marking, clean edges, uniform black appearance, and minimal burrs.
• 10 ns: Balanced result with moderate depth.
• 30 ns: Slight edge melting may begin to appear.
• 80 ns: More obvious melting, burrs, and uneven darkening may appear.

12. MOPA Pulse Width Recommendations by Material

• Black marking on anodized aluminum: Short pulse width, approximately 3–6 ns.
• Black marking and grayscale images on stainless steel: Short pulse width, approximately 4–8 ns.
• Bare 6061 aluminum: Medium pulse width.
• Deep engraving on metal: Longer pulse width, approximately 50–120 ns.
• Plastic and PCB marking: Shorter pulse width to reduce excessive burning.

13. Final Tips for Adjusting Fiber Laser Settings

There is no single set of laser parameters that works perfectly for every material.

When adjusting your fiber laser settings, remember:

• Power mainly affects engraving intensity and depth.
• Speed controls how long the laser interacts with the material.
• Frequency controls pulse density and overlap.
• MOPA pulse width controls the duration of each laser pulse and changes the thermal characteristics of the process.

Start with conservative settings, make small adjustments, and test on the actual material before beginning production.