Diode, CO₂, fibre and the odd one out

Three of the four labels on a laser spec sheet tell you what makes the light. The fourth, UV, tells you where that light falls on the spectrum. Once you see the difference, every comparison built on those labels reads differently.

Laser Workbench. Desk research from manufacturer and technical sources, checked 17 September 2026. We have not tested any of the machines mentioned.

Diode, fibre and CO₂ are sources, drawn at the wavelengths used in their manufacturers’ examples. Ultraviolet is not a source but a stretch of the spectrum, reached in the examples we looked at by converting infrared light to a shorter wavelength. Wavelength on a logarithmic scale. Laser Workbench drawing from sources 1, 2, 4 and 6.

Anyone shopping for a laser is offered four families: diode, CO₂, fibre and UV. They look like four answers to the same question. They aren’t.

Diode, CO₂ and fibre each name a source, the physical thing inside the machine that produces the beam: a semiconductor chip, an electrically excited gas, a length of specially treated optical fibre. UV names a region of the spectrum, the wavelengths shorter than visible violet light. A UV machine still needs something to make its light, and in both of the examples we examined that is an infrared laser whose output has been converted to a shorter wavelength.

This is more than pedantry. When one of the four labels answers a different question from the other three, a comparison that lines them up side by side has gone slightly wrong before anyone has mentioned watts.

What each label tells you

Diode: a chip, and not just one colour

A diode laser makes its light in semiconductor material. Trotec’s industrial guide describes a blue source at 450 nm,¹ and blue is what most buyers picture. But the label doesn’t fix the wavelength. Trotec’s fibre-laser guide notes that diodes also operate in the infrared, at around 808–980 nm depending on type.²

Product pages blur this quickly. xTool’s UK page for the S1 offers 40, 20 and 10 W diode options and, separately, a 2 W infrared module at 1064 nm.³ One chassis, more than one kind of light. When a spec sheet says “diode”, find out which module you are getting and what wavelength it emits.

CO₂: a gas, far out in the infrared

A CO₂ laser draws its light from an electrically excited gas mixture. Trotec places the output in the mid-infrared, between roughly 9 and 11 µm, with the 10.6 µm line often the strongest.⁴ That is more than twenty times the wavelength of a 450 nm blue diode.

The gap matters because materials respond to different wavelengths differently. Trotec’s diode guide puts it plainly: whether a material works with a diode laser depends on how well it absorbs 450 nm light, and a material that is transparent at that wavelength lets the beam pass straight through.¹ What a machine can process starts with its wavelength, before its power rating comes into it.

Fibre: the fibre is the laser

In a fibre laser the light is generated and amplified inside optical fibre that has been doped with a rare-earth element such as ytterbium.^2,5 Trotec gives 1064 nm as the typical wavelength for the marking lasers it describes,² but that figure describes those examples rather than every fibre laser.

Workshop buyers usually meet fibre in compact marking machines that steer the beam with galvo mirrors. That is one kind of machine built around the source. The same architecture turns up at other wavelengths, powers and pulse regimes, in very different equipment.

UV: the odd one out

UV describes where the output falls on the spectrum, not how it is made. In the examples we looked at, it is made by conversion. IPG explains how passing an infrared fibre-laser beam through a non-linear crystal halves its wavelength, and how repeating the step halves it again.⁶ Coherent’s AVIA LX 355 is a solid-state laser whose 355 nm output comes from harmonic conversion.⁷

Even inside the ultraviolet the vocabulary shifts. IPG reserves “deep UV” for wavelengths shorter than 300 nm,⁶ so a 355 nm machine is ultraviolet but not deep UV by that definition. xTool’s F2 Ultra UV is a 5 W, 355 nm product.⁸ Like the AVIA, it is one product, and neither tells you how every UV machine is built or behaves.

UV is sometimes sold as a “cold” process. The label cannot promise that on its own: how much heat reaches the work depends on the source, the pulse and the job, and the name of the wavelength band settles none of those.

What each type is sold for

Manufacturers publish their own lists of what each type of laser handles, and those lists follow the spectrum above. Set side by side, the reasons they give come back to wavelength. The statements below are the makers’ own general claims, so treat them as a guide to what is worth investigating, not a promise about your material or your machine.

What Trotec and IPG say each type suits, and why
Type	The maker says it suits	The maker says it struggles with	The wavelength reason given
Blue diode450 nm	Organic materials such as wood, leather and paper; marking some metals and plastics; cutting only thin material such as plywood, paper and card.¹	Cutting clear or transparent acrylic, clear glass, and dense materials such as stone and ceramic.¹	A material that doesn’t absorb 450 nm light lets the beam pass through.¹
CO₂10.6 µm	Wood, acrylic, glass, paper, textiles, plastics, foils and films, leather and stone.⁹	Metals: Trotec describes CO₂ as mainly for non-metals, though high-power CO₂ lasers are also used in industrial metalworking.^4,9	Trotec links the 10.6 µm wavelength to its suitability for non-metals and most plastics.⁹
Fibre1064 nm	Metals, coated metals and plastics, and to some extent ceramic; marking is the typical job.^2,9	Not stated in these sources.	Metals absorb 1064 nm light strongly.²
UVBelow 400 nm	Fine processing of polymers and other non-metals.¹⁰	Not stated in these sources.	Shorter wavelengths focus to a smaller spot, and UV is absorbed in a shallow surface layer.⁶

Manufacturer statements checked on 17 September 2026. They describe typical uses, not results on any particular material or machine.

A material name is only the start. Before you cut anything, find out what the sheet in front of you is actually made of: our materials guide works through what a supplier’s safety data sheet can and cannot tell you.

Why watts don’t settle it

Power is the number manufacturers lead with, and it matters. But it is one of several properties that decide what happens when the beam meets the work. IPG’s technical overview treats wavelength, average power, operating mode, spot size and beam quality separately, because each changes how energy reaches the target.⁵ Twenty watts of blue light, twenty watts at 10.6 µm and twenty watts of pulsed 1064 nm light are not three sizes of the same thing.

The watts themselves need unpacking, too. A spec sheet may quote average optical power, peak power or electrical input power, and it may quote the figure for one configuration of a machine sold in several. Before comparing any two machines, get answers to six questions.

Six questions for any spec sheet

Which source?: Which laser module is actually supplied, and what wavelength does its documentation give?
Pulsed or continuous?: If pulsed, what pulse regime and operating range does the maker state?
Which watts?: Average, peak or input power, and for which configuration?
How is the beam moved?: Gantry or galvo, and with which lens, work field and focus conditions?
On what?: The specific material, its thickness and finish, and the operation you need.
Who says so?: The manufacturer, an independent test with its method published, or nobody yet?

Four machines, four lessons

We read four current UK product pages to see how these labels behave in practice. All four happen to come from one manufacturer, and none of this is a recommendation: every figure below is xTool’s own, as published on 17 September 2026.

What four product pages state, and what each one shows
Product	What the page states	What it shows
xTool S1³Diode, plus infrared module	40, 20 or 10 W diode options, and a separate 2 W, 1064 nm infrared module. Bed 23.93 × 15.16 in; work area 19.6 × 12.5 in.	One chassis can carry different light sources. It also shows why bed size and work area must be kept apart: the work area, the smaller figure, is the one to measure your largest job against.
xTool P2/P2S¹¹CO₂	55 W CO₂. Bed size given as 26 × 14 in in the page’s metadata and 23.6 × 12 in in its product-variant copy.	The page contradicts itself, and its web address and title say P2 while the product shown is the P2S. We have used neither bed figure. Copying the larger one into a comparison would look precise and be indefensible.
xTool F1 Ultra¹²Fibre and diode	A 20 W fibre laser and a 20 W diode laser in one machine.	A single product belongs to two families, so any comparison has to be made module by module.
xTool F2 Ultra UV⁸UV	5 W at 355 nm.	The UV label places the output on the spectrum. The source, the pulse behaviour and results on any given material are separate questions.

Figures in orange are where the manufacturer’s page disagrees with itself.

Using the labels when you shop

Start from the job rather than the family: the material, what you need to do to it, the largest piece you will handle, how many you will make and the room the machine will live in. Then ask which kinds of source are worth researching for that job. The label narrows the search. It cannot tell you whether a particular machine will do your work, fit your space or be safe to run there.

When you reach individual machines:

Name the source, the module and the wavelength, not just the family.
Keep bed size, work area, pass-through and lens field as separate figures.
Keep each manufacturer’s material claims attached to the model and conditions they were made for.
Check guarding, enclosure, interlocks, extraction and services in that machine’s own documentation.
Where a figure is missing, write “not stated”. Where two sources disagree, write down both.

Safety. The laser type does not determine a machine’s safety class, whether its enclosure is adequate, what extraction it needs or what protective equipment is required. Those answers come from the machine’s own documentation, the safety information for the material, and the requirements that apply where you work.

Next: turn your job into a brief before you shortlist machines.

Sources

All pages checked on 17 September 2026. Product figures are the manufacturers’ own.

Trotec UK, “Diode lasers: the guide to precision marking, engraving and cutting”. Manufacturer’s technical guide.↩
Trotec UK, “Fibre laser guide”. Manufacturer’s technical guide.↩
xTool UK, S1 product page. Manufacturer’s product page.↩
Trotec UK, “CO₂ lasers: functionality and areas of application”. Manufacturer’s technical guide.↩
IPG Photonics, “Fiber Lasers 101”. Manufacturer’s technology overview.↩
IPG Photonics, “Deep UV Fiber Lasers”. Manufacturer’s technology overview.↩
Coherent, AVIA LX 355-Q25 data sheet. Laser-source data sheet (PDF).↩
xTool UK, F2 Ultra UV product page. Manufacturer’s product page.↩
Trotec, “Laser types in comparison: CO₂ laser vs. fiber laser”. Manufacturer’s FAQ.↩
IPG Photonics, “Ultraviolet Ultrafast Fiber Lasers”. Manufacturer’s product-family page.↩
xTool UK, P2/P2S product page. Manufacturer’s product page; contains the conflicting bed sizes described above.↩
xTool UK, F1 Ultra product page. Manufacturer’s product page.↩

Spotted an error? Our corrections page explains how to report it. How we handle manufacturer claims is set out in How we compare.