Pulse Width in Nanoseconds: What It Does to Your Mark

Understanding pulse width in nanoseconds is key to controlling how your MOPA fiber laser interacts with materials. We explain what it means and how it affects your marks on the bench.

31 August 2026 · The HagoLaser team · 6 min read

Pulse Width in Nanoseconds: What It Does to Your Mark

What is Pulse Width, Anyway?

When you're trying to get a specific mark from your fiber laser, you adjust power, speed, and frequency. But if you have a MOPA source, there’s another critical setting: pulse width, measured in nanoseconds (ns). It controls the duration of each individual burst of laser light. Think of it like this: if frequency is how many times you tap a nail with a hammer per second, pulse width is how long each individual hammer blow lasts. A short tap might not do much, but a longer, more sustained push can have a very different effect, even if the overall power of your arm remains the same. On a MOPA laser, you can adjust this duration. Q-switched lasers, by contrast, have a fixed pulse width set by the manufacturer – which is why MOPA sources are so much more versatile for different materials and marking styles. If you want to dive deeper into the differences, we have an article on MOPA vs Q-switched Fiber Lasers: What Changes on the Bench. Before we go further: a fiber marking laser is a Class 4 machine. The invisible 1064 nm beam and its reflections cause permanent eye damage instantly. Always wear laser safety glasses rated for 1064 nm with an OD suitable for your source power. Ensure proper fume extraction is running, and never leave a job unattended. Physical enclosures are your real safety.

Long Pulses: Digging Deep and Cutting Through

When you set a longer pulse width, you're telling the laser to deliver more energy in each individual pulse. This is like turning that hammer tap into a sustained push. What does that mean on your bench?

Deeper Engraving: Longer pulses are excellent for ablating material and creating depth. They put more energy into the material, melting and vaporizing it more aggressively with each shot. If you need to engrave a design that will be filled with enamel, for example, a long pulse width is your friend.
Efficient Cutting: For cutting metal, long pulses contribute to the overall energy delivery needed to get through the material. Combined with the right frequency and wobble settings, they help remove molten material and advance the cut.

Our 100 W MOPA source exposes a fixed table of pulse widths, ranging from 2 ns all the way up to 250 ns. For our everyday sterling silver engraving, which we often fill with enamel, we use a pulse width of 200 ns. This longer pulse helps us achieve the necessary depth efficiently.

Pulse Width, Frequency, and Energy Per Pulse

It's important to remember that pulse width works in conjunction with frequency and average power. The actual "punch" of each individual shot, or the energy per pulse, is roughly calculated as your average power divided by your frequency. For example, our engraving recipe for silver that gets filled with enamel uses 100 % power · 600 mm/s · 30 kHz · 10 passes. Notice that 30 kHz frequency. We found that dropping our frequency to 30 kHz was a big lever for depth. This is because lower frequency (fewer pulses per second) means each pulse carries more energy, especially when combined with a long pulse width like 200 ns. This combination allows us to dig deeper, matching the results we saw from a 30 W machine that was also running at a lower frequency. However, for cutting, the opposite is true for frequency. We tried dropping our silver cutting recipe to 20 kHz (which, again, would mean fatter pulses), but it cut worse. For cutting through, a higher frequency (like our standard 60 kHz for silver) wins, allowing the beam to move more continuously and eject melt effectively.

Short Pulses: Gentle Marks and Color

Now, consider the other end of the spectrum: short pulse widths, typically in the 2 to 20 nanosecond range on our machine. These are like those gentle taps with the hammer.

Gentle Surface Marking: Short pulses deposit less energy per shot. This makes them ideal for delicate surface marks on materials like plastics, anodized aluminum, or for creating fine details without excessive material removal.
Color Marking on Metals: This is where short pulses truly shine. The precise, low-energy interaction of short pulses with the surface of certain metals, particularly stainless steel, allows for the creation of various colors by manipulating the oxide layer. This effect is not possible with the high-energy ablation of long pulses.

While we mainly focus on silver, understanding that short pulses enable this gentler interaction is crucial for anyone working with a wider range of materials.

Our Pulse Width Settings in Practice for Silver

Let’s look at how pulse width fits into our real-world recipes for sterling silver at Joyería HAGO. Our usual setting for engraving sterling silver, which aims for good depth and clean lines, looks like this:

Speed: 700 mm/s
Power: 95 %
Frequency: 40 kHz
Pulse width: 200 ns
Passes: 5

This combination of moderate frequency and long pulse width gives us a good balance of depth and detail for general engraving. For cutting sterling silver sheet, the recipe is different:

Power: 95 %
Speed: 190 mm/s
Frequency: 60 kHz
Pulse width: 200 ns
Wobble: enabled, with a diameter of 0.15 mm

Notice that even for cutting, we use a long pulse width (200 ns). This is because the goal is still to deliver significant energy to cut through the material, and the long pulse aids in that. The higher frequency (60 kHz) is critical for efficient material ejection when cutting. If you’re cutting gold, the same recipe applies, but with fewer passes because gold absorbs more of the beam. Here is our starting point table for gold (remember, these are derived from our silver numbers and must be proved on scrap before use):

Sheet thickness (mm)	Gold passes (starting point)
0.25 - 0.4	2
0.5	3
0.6	4
0.7	6
0.8	9
0.9	11
1.0	14

For comparison, our measured silver at the same settings would need 17 passes for 0.8 mm, 21 for 0.9 mm, and 28-29 for 1.0 mm. You can find more detail in our article Cutting Gold with a Fiber Laser: Where We Would Start.

Practical Takeaways for Your Bench

Understanding pulse width finally clicked for us after too much wasted silver. Here’s what we learned:

Pulse width is a MOPA superpower. If you have a MOPA source, use this setting! It offers a level of control over material interaction that Q-switched lasers simply don't have.
Go long for depth and cutting. When you need to engrave deep, or cut through metal, opt for longer pulse widths (e.g., 150-250 ns on our machine). They deliver more energy per individual pulse.
Go short for gentle marks and color. For delicate surface marking, working with plastics or anodized aluminum, or achieving color marks on steel, shorter pulse widths (e.g., 2-20 ns) are what you need.
Pulse width is a source setting. Unlike speed or power, which are often set per "pen" in EzCad3, pulse width is usually a global setting for the laser source itself. You set it once, and it stays that way until you change it. Always double-check your current pulse width setting before starting a critical job.
Test, test, test. Our numbers are for our machine, our 100 W MOPA source, and our sterling silver. Your results will vary. Always calibrate on scrap of the same alloy and thickness, changing only one variable at a time until you find the perfect recipe.