FoundationsModule 1.1~3 min read

Inside a Fiber Laser: MOPA vs Q-switched

A fiber laser produces a 1064 nm beam that metals absorb strongly. Two source types dominate the market, Q-switched (cheaper, fixed pulse width) and MOPA (premium, variable pulse width). The difference between them determines what your laser can actually do.

How a fiber laser works

A seed diode injects a small pulse of light into a doped optical fiber. That fiber is "pumped" by other diodes, amplifying the pulse to hundreds of watts of peak power before it leaves the collimator and reaches the galvo head. Two tiny mirrors steer the beam through the F-theta lens onto the work surface.

Wavelength: 1064 nm (near-infrared), invisible to the eye.
Spot size: tens of microns. Far smaller than CO2.
Workflow: raster + vector all happen in the galvo, not on a moving gantry.

Q-switched vs MOPA: the difference that matters

Cheap fiber lasers are Q-switched: pulse width is FIXED (typically 80-140 ns), and you only control frequency, power, and speed. MOPA (Master Oscillator Power Amplifier) lets you also control pulse width, anywhere from ~2 ns to ~500 ns.

That extra knob is what unlocks:

Color annealing on stainless and titanium (long pulses grow thicker oxide layers for vivid colors).
Clean dark marks on anodized aluminum (short pulses don't burn through the dye into the metal underneath).
Plastic marking without melting craters (short pulses, low average power).
Photo engraving on metal with finer dither patterns (short pulses preserve detail).

If you have a MOPA, use the pulse width

If you leave Q-pulse at 200 ns for every job, you're paying MOPA prices for Q-switched output. Color annealing, dark marks on anodized AL, and plastic marking all want different pulse widths. Tune it.

Common source brands inside fiber lasers

Most consumer/prosumer fiber lasers use one of three source brands. The brand of your machine (OMTech, ComMarker, Cloudray, Thunder, etc.) is just the cabinet, the source inside is one of these:

JPT: premium MOPA. M6, M7, M8 series. Excellent beam quality, full pulse-width range, generous frequency range. Common in mid/high-end machines.
Raycus: solid Q-switched. Fixed pulse width, narrow freq band. Workhorse for budget machines. Very reliable.
Max: budget Q-switched. Like Raycus but cheaper.
IPG: top-tier industrial. Rare in consumer machines; common in big production fiber lasers.

When community recipes mention "JPT 60W MOPA" or "Raycus 30W," they're naming the source, the brand of your machine is secondary. Settings transfer better between same-source lasers than between same-brand lasers with different sources.

Wattage in fiber lasers

Common consumer wattages: 20W, 30W, 50W, 60W, 100W.
Higher wattage = faster, deeper, more capable on hard materials. Roughly halves engrave time per doubling.
For most small-business work, 30W or 60W is the sweet spot. Below 30W struggles with deep engrave; above 100W is industrial pricing.
Wattage doesn't affect WHICH materials you can mark, just how fast.

Frequency range

Q-switched: narrow, typically 20-80 kHz or 50-100 kHz.
MOPA: wide, typically 1 kHz to 4000+ kHz.
The MOPA's wider range is why it can do both ultra-aggressive deep engraves AND ultra-fine color annealing at low power.

Software

Most fiber lasers ship with EZCAD (basic, free, dated UI). Replacing it with Lightburn (Galvo edition) is the standard upgrade path, better UI, image modes (3D Sliced for relief), Material Library, sublayers. Both software talk to the same controller boards (BJJCZ / JCZ).