What's the difference between a fiber laser and a diode laser?
More importantly, which laser do you need for your application?
While fiber lasers are significantly more expensive compared to diode lasers, they are also much more powerful.
However, if you're doing small hobby projects in your garage shop, a fiber laser might be overkill.
Before you decide to go with one of these, it's important to understand the right applications for each.
In this article, I have discussed and compared fiber laser and diode laser technologies based on their features, advantages, and applications.
Difference Between Fiber Laser and Diode Laser
Although fiber and diode lasers are solid-state lasers with similar light sources, there are differences in their features and applications.
The wavelength of a laser greatly impacts the absorption rate of the laser energy by various materials.
A general rule of thumb is that the shorter the wavelength of light, the higher its energy will be.
Fiber laser has a wavelength of 1060 nm, which is readily absorbed by metals.
Whereas diode lasers have wavelengths ranging from 550 nm to 950nm, which falls in the visible light region of the electromagnetic spectrum.
This wide range of wavelengths makes diode lasers very effective over various materials, including metals and non-metals.
Despite being a fairly new technology, Fiber laser has seen some rapid developments over time.
Due to these developments, fiber lasers are available in various power options from as low as 10W up to 15kW.
On the other hand, a diode laser with a power output of 20W, such as xTool D1 Pro, was very rare to find until recently.
Teradiode introduced a technique that combines the output of various diodes to form a single laser beam with a high-power output of up to 8kW.
Fiber lasers offer little in terms of material flexibility.
The wavelength of fiber laser is only suitable for laser cutting or engraving metal workpieces, which makes its area of application very limited.
However, when laser cutting or engraving transparent materials, a diode laser passes through the material without causing any significant effect on the surface of the workpiece.
If you need flexibility in terms of materials but more power than a diode laser, a CO2 laser might be what you need.
A common solution to this is using dark-colored paint or masking tape to cover the transparent surface so that the diode laser does not pass through it.
Material flexibility of fiber laser and diode laser
One of the most important reasons for the increasing popularity of fiber lasers is their high cutting speed.
A 4kW fiber laser can cut through a 0.12” thick aluminum at a cutting speed of 402 ipm, which is 3-4 times faster than a CO2 laser.
But a diode laser can offer a cutting speed 15% faster than a fiber laser of the same power rating.
It gives the best results on aluminum with up to 30% faster-cutting speed than fiber lasers.
The table below can give you a better understanding of the difference between the cutting speed of a fiber laser and a diode laser.
|2kW Fiber Laser
Cutting speed (ipm)
|2kW Diode Laser
Cutting speed (ipm)
|Stainless Steel (0.04")
|Stainless Steel (0.35")
Comparision of cutting speed of fiber laser and diode laser
The ability of a laser to cut through thick material is greatly affected by its power.
A diode laser was primarily used for cutting and engraving thin materials because of its low laser power.
The recent developments and availability of higher power options (up to 8kW) have made it possible for diode lasers to cut through thick materials.
But the availability of fiber laser in even higher power options (up to 15kW) makes it the ideal choice for laser cutting thick materials.
Although the cuts produced by both the lasers have very small kerf width, a diode laser produces cuts with a slightly tighter tolerance than a fiber laser.
Diode lasers also produce cuts with far superior edge quality than a fiber laser regardless of the type of material and its thickness.
Compared to other lasers such as CO2 and Nd: YAG laser, fiber lasers have a smaller footprint and are more portable.
But diode lasers revolutionized the portability of lasers by its extremely small size.
A 5-6W diode laser module can be small enough to fit in your hand and weigh around 0.4lbs (200gm).
These small diode lasers can be powered by a portable power brick with a power output of 12V.
The compact design, lightweight, and low power operation make diode lasers ideal if you're looking for a portable laser engraver or cutter.
The overall cost of a laser cutter constitutes of the initial cost or cost of purchase and the average operational cost.
Desktop size fiber lasers with a power rating of 30W to 50W can cost around $5000.
But a high-end fiber laser with a power rating of above 1kW will start from $40,000.
A low-powered diode laser (5W - 6W) is comparatively very cheap, with a starting price of around $299.
These low-priced diode lasers are an excellent choice for beginners and DIY enthusiasts who are willing to explore and start making interesting DIY projects using laser cutters and engravers.
However, a high-power diode laser with a power rating above 1kW is fairly new to the market and can cost much higher than a fiber laser of a similar caliber.
Compared to a CO2 laser, fiber lasers are highly efficient and have comparatively lower operational costs.
But the diode lasers offer a wall plug efficiency of around 45%, which is much better than the 35% efficiency of fiber lasers.
This reduces the average operational cost of diode lasers, making them more cost-efficient than fiber lasers.
Fiber lasers are solid-state lasers and are known for low maintenance requirements as there are no moving parts or mirrors involved.
But a single damaged optical fiber can sometimes lead to the changing of the entire laser module, which can be very expensive.
Diode lasers are also solid-state laser and hence has less maintenance requirement.
Moreover, as no fiber optics are involved in diode lasers, it also eliminates the risk of a damaged fiber cable.
The only risk for a diode laser is the overheating of the laser module which is delt by a dedicated cooling system, such as a simple cooling fan.
Final Thoughts - Fiber Laser vs Diode Laser
Although recent developments have made it possible to reach high power output in a diode laser, there aren't many high-power diode laser cutters available.
The technology is also relatively new, making it difficult to get a predictable outcome, especially while working with thick metal sheets.
On the other hand, high-power fiber lasers are readily available in the market.
As fiber lasers have been around for a longer time, they are a more proven and reliable technology.
However, a low-powered diode laser is an excellent choice for a beginner or a DIY user, as it is easily available at affordable prices and can engrave various materials.
These low-powered diode laser engravers can also perform reasonable cuts in thin materials using the multi-pass technique.
What is a Fiber Laser?
A fiber laser is a diode-pumped solid-state laser (DPSSL) that uses a semiconductor diode as a light source.
The light from the diode source then enters the core of the fiber laser, which is doped with a rare-earth element (ytterbium, erbium, or thulium).
These rare-earth elements absorb the light from the diode source and transform it into a laser light of desired wavelength (950 nm to 2200 nm).
Fiber lasers get the name from their laser delivery system that uses fiber optics cable to transfer the laser to the laser head.
At the laser head, the laser is passed through a focusing lens that generates a highly focused laser beam to cut, engrave or etch the metal.
What is a Diode Laser?
A diode laser is a solid-state laser that uses the radiations directly from the semiconductor diode without any doping medium.
Due to this reason, diode lasers are also known as DIrect Diode Lasers (DDL).
The elimination of the doping medium also eliminates the need for fiber optics, which makes diode laser very compact and energy-efficient.
Diode lasers have been around for a long time and have been used in laser pointers, optical mouse, CD/DVD/Blu-ray disc reading, and recording.
But with the advancement in technology, these diode lasers can now be used for laser cutting, engraving, and marking various materials.
Frequently Asked Questions (FAQ)
What is wall plug efficiency of a laser?
The wall-plug efficiency of a laser module is the ability to convert electric energy into laser energy. The higher the wall-plug efficiency, the greater the ability of a laser to cut or engrave a material with less electricity consumption.
A diode laser has a wall plug efficiency of 45%, which means that it converts 45% of the electric energy supplied to it into laser energy.
What is a blue light diode laser?
A blue light diode laser is a light beam with a 400-500 nm wavelength that is visible to the human eye as blue or violet light.
Blue light diode laser gained popularity after the trio who invented it received a Nobel Prize in 2014 for their invention.
The shorter wavelength of the blue laser makes it highly efficient and enables it to attain a significantly smaller spot size than the other lasers.
Copper, which is a challenging material to cut or engrave by laser, readily absorbs the radiations in this wavelength range. This makes blue laser very efficient in cutting, engraving, and welding copper.
Can we cut transparent materials with a diode laser after covering the surface with dark-colored paint?
Yes, using dark-colored paint over the transparent material can enable a diode laser to cut through extremely thin sheets of the material.
This technique gives the best results for engraving transparent materials but it cannot cut thick materials.