What is a Fiber Laser? Simply Explained

What is a Fiber Laser? Simply Explained

What is a Fiber Laser? Simply Explained

Fiber lasers are one of the most commonly used lasers in manufacturing.

They offer high energy concentration with good accuracy, making them ideal for intricate laser applications.

This article discusses fiber lasers in detail along with their advantages, applications, and limitations.

I have also laid out the differences between fiber lasers and other lasers like CO2 and diode lasers.

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Fiber Laser- Introduction

Working of a fiber laser
Working of a fiber laser

A fiber laser is a type of solid-state laser that has an optical fiber as the laser gain medium. The host medium in fiber lasers is usually glass doped with rare-earth impurity ions, which increases its efficiency. Fiber lasers are used for various applications, ranging from medical procedures to metal processing.

A law-powered diode laser is used for pumping the fiber laser and the generated laser is guided through the optical cable and passed through an amplifier. 

After amplification, the laser beam is tuned to a particular wavelength and emitted out of the optical cable as a laser. 

Fiber lasers operate in the wavelength range of 780–2200nm, which lies in the infrared region of the electromagnetic spectrum and is not visible to the naked eye.

Types of Fiber Lasers

Fiber lasers, one of the most popularly used types of laser, can be differentiated based on their source, mode of operation, laser output power, and core diameter.

On the Basis of Laser Source

The wavelength of a fiber laser depends upon the doping material used for generating the laser.

Thulium fiber laser, with a wavelength of around 2000nm, is used for various medical treatments, like breaking down kidney stones and treating other soft tissue conditions.

Erbium-doped fiber laser generally has a wavelength of around 1500-1600nm and is used for various applications like optical components testing, spectroscopy, pumping other lasers, etc.

Ytterbium fiber laser, with a wavelength of 1060nm, is widely used in manufacturing industries for various applications like cutting, engraving, welding, etc.

On the Basis of Operation

Fiber lasers can be operated in pulsed-wave and continuous-wave modes.

In continuous-wave fiber lasers, the power and intensity of the laser are constant throughout the operation.

This type of laser is best suitable for material processing applications like cutting and welding, which require high speed and uniformity.

In a pulsed-wave fiber laser, the laser output is in the form of pulses (short bursts) of a high-energy laser with a fixed time interval.

Although the peak power of a pulsed-wave laser may exceed that of the continuous-wave laser, they have lower average energy than continuous-wave lasers.

Pulsed-wave lasers are suitable for intricate applications like engraving and spot welding, where high precision is desirable over cycle time. 

On the Basis of Laser Power

All types of lasers can be differentiated on the basis of their laser output power.

Lasers with higher power output will generate more energy than low-powered lasers, which improves processing speed.

As a result, low-powered lasers are most commonly used for fine detailing applications where precision is valued over time.

Whereas higher-powered lasers are suitable for heavy-duty applications like making heavy cuts and drilling deep holes with quick cycle time. 

On the Basis of Core Diameter

The core through which the light travels can either be single-mode or multi-mode. 

Based on the model of the core, its diameter also varies.

The estimated core diameter for single-mode fiber lasers is around 8-9 microns and 50-100 microns for multi-mode. 

Fiber lasers with smaller core diameters are generally more efficient at transmitting light and thereby provide better beam quality than fiber lasers with larger core diameters.

Applications of Fiber Lasers

A fiber laser cutter working on a stainless steel pipe
A fiber laser cutter working on a stainless steel pipe

The most common application of fiber lasers is in the field of manufacturing.

The wavelength of fiber lasers is readily absorbed by metals, making them ideal for applications involving metal processing. 

As a result, fiber lasers are commonly found in metal laser engravers and metal laser cutters.

Although fiber lasers are not recommended for processing non-metals, a MOPA Fiber laser can be used on plastic workpieces and produce colored engravings on certain materials. 

Furthermore, the shorter wavelength of fiber lasers makes it possible to focus the laser in a tight spot, thereby increasing its energy density and ability to perform cleaner cuts.

The amplifier in the laser medium of fiber lasers can provide very high gain, thus allowing for very high laser output power. 

Fiber lasers can be used for various applications like metal cutting, engraving, drilling, welding, cleaning, marking, and cladding. 

These lasers are also used for medical procedures and diagnostics, such as treating kidney stones and other soft tissue conditions.

The ability of a fiber laser to travel long distances without any energy loss or disturbance makes it ideal for quick communication over long distances.

Advantages of Fiber Lasers

Fiber lasers are generally compact with a small footprint and lightweight, which offers good portability and allows them to be set up in small workspaces.

These CNC machines offer various advantages over traditional machining operations.

Fiber lasers can be used for machining almost every type of metal, like aluminum, stainless steel, mild steel, copper, titanium, etc. 

Apart from metals, MOPA Fiber lasers can also work on non-metals like plastics, ceramics, silicone, and textiles. 

Single-moded fiber lasers offer extremely good beam delivery with minimum energy loss and compact spot size.

This minimizes the heat-affected zone, thereby preventing the workpiece and laser optics from being damaged due to overheating.

The external cladding layers on the optical fiber reduce external interference, which makes fiber lasers suitable for transmitting signals over long distances with minimum disturbance.

Therefore, fiber lasers are also used in the telecom industry for transferring data and signals over the network.

The thin and flexible laser medium allows for long optical fibers which can increase the optical gain of the laser beam. 

Long fiber cables also enhance heat dissipation and reduce the need for a cooling system. 

How are Fiber Lasers Different from Other Lasers

fiber lasers vs CO2 lasers

Fiber laser vs CO2 laser
Fiber laser vs CO2 laser

In the table below I have mentioned the basic differences between fiber and CO2 lasers.

ParameterFiber LasersCO2 Lasers
Gain mediumOptical fiberCO2 gas
Wavelength780-2200 nm9600-10600 nm
Spot sizeSmallerLarger
Material capabilityMetals like mild steel, stainless steel, copper, brass, etc.Steel, aluminum, acrylic, glass, wood, etc.
Cutting speed
(0.04" thick aluminum)
Fast
4kW fiber laser - 2126 ipm
Comparatively slow
4kW CO2 laser - 420 ipm
MaintenanceLow to moderateModerate to high

Basic differences between fiber lasers and CO2 lasers

Fiber lasers have an operational wavelength of 780–2200 nm, whereas CO2 lasers have an operational wavelength of 9600–10600 nm.

This wavelength of fiber lasers allows them to be easily absorbed into metals, which makes them most suitable for metal processing.

However, MOPA fiber lasers can be used on non-metals and to perform colored engravings on certain plastics.

This makes fiber lasers suitable for cutting and engraving metals, whereas CO2 lasers are ideal for cutting and engraving non-metals.

However, a high-powered CO2 laser can perform through cuts in various metals like stainless steel, tungsten, aluminum, etc. except shiny metals like copper, brass, silver, and gold.

Fiber lasers have a smaller spot size than CO2 lasers, allowing them to perform detailed engravings on intricate parts.

Smaller spot size also increases the energy density of the laser, enabling them to perform clean cuts at a faster rate than other lasers.

CO2 lasers need regular maintenance like mirror/lens cleaning, gas refill, checks in bellows, alignments, etc. This can take up to 4-6 hours per week in certain cases.

Fiber lasers on the other hand have very low maintenance. The optical fiber has external cladding that protects the fiber from external damage.

However, if the optical fiber is somehow damaged, you will need to change the whole laser module which can become very costly.

fibers lasers vs diode lasers

Fiber laser vs diode laser
Fiber laser vs diode laser

In the table below I have mentioned the differences between fiber and diode lasers.

ParameterFiber LasersDiode Lasers
Gain medium Optical fiberSemiconductor
Wavelength780-2200 nm550-950nm
Material capabilityMetals like steel, aluminum, brass, copperMetals and non-metals except clear glass
Cutting speedSlower than a diode laser with same power Faster than a fiber laser with same power
MaintenanceLow to moderateLow to moderate

Basic differences between fiber lasers and diode lasers

Fiber lasers have an operational wavelength of 780-2200 nm and diode lasers operate in the 550-950nm range.

Diode lasers can be used on most metals and non-metals except clear glass as the diode laser beam passes through without any significant effect.

These lasers are generally used in low-power desktop lasers, whereas fiber lasers are found in DIY as well as industrial laser cutters.

The edge finish of diode lasers is always better than fiber lasers, regardless of the material.

Although fiber lasers are available in compact sizes, diode lasers are even smaller, and 5-6W diode lasers are compact enough to fit in your hand.

Diode lasers are low-maintenance lasers. However, they tend to overheat and require a dedicated cooling system for optimal operation.

High-powered diode lasers, such as xTool D1 Pro, are excellent alternatives to fiber lasers as they can be used for various engraving applications on different metals.

What is a Fiber Laser Cutter?

Fiber laser cutters are CNC (Computer Numerical Control) machines that are widely used in the manufacturing industry.

These machines are automated with the help of a computer system that guides the movement of the laser head to perform the desired operation.

A CNC fiber laser provides the flexibility to control various parameters like laser power, speed, focus, etc., making it possible to use the same machine for cutting and engraving applications.

These laser cutters are popularly used in laser cutting metal, laser engraving metal, and other sheet metal laser applications.

frequently asked questions (FAQ)

Can a fiber laser engrave glass?

No, a fiber laser cannot engrave glass as the laser passes through it without producing a significant effect. But using a fiber laser to engrave a glass workpiece placed on a metal sheet will result in a black marking on the back surface of the glass, produced due to the backlash effect of the laser from the surface of the metal sheet.

What is the wall plug efficiency of fiber lasers?

The wall plug of fiber lasers is around 35%, which means that a fiber laser converts 35% of total electrical energy into useful laser energy.

Can fiber laser be used for machining silver?

Yes, fiber lasers can be used for machining silver. However, silver needs special care when processed under a laser. It tends to retain the heat and deform during cutting operations. Hence, heat sinks should be used when processing silver using fiber lasers.

About John

Hey I'm John. I talk about CNCs and Power Tools at Mellowpine. I'm a CNC hobbyist who has been making CNCs and writing about CNCs for a while. I currently also work as a consultant for business owners and hobbyists setting up their own CNCs. If you have any questions related to CNC, I'd be happy to answer them. Reach me at john@mellowpine.com

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John

Hey I'm John. I talk about CNCs and Power Tools at Mellowpine. I'm a CNC hobbyist who has been making CNCs and writing about CNCs for a while. I currently also work as a consultant for business owners and hobbyists setting up their own CNCs. If you have any questions related to CNC, I'd be happy to answer them. Reach me at john@mellowpine.com

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