Master Oscillator Power Amplifier, commonly called MOPA, is one of the most recent innovations in fiber laser technology.
Its ability to perform color markings on stainless steel materials and the ability to engrave on plastic without burning has attracted a lot of attention.
With the entry of MOPA laser technology in engraving applications, it has become the second most used pulsed fiber laser technology, the first one being Q-switch.
This article will explain MOPA fiber laser technology in-depth such as its working, applications, advantages, and disadvantages.
In the last sections, I've compared MOPA fiber laser technology to the most commonly used Q-switch fiber laser technology.
At the end of this article, I've suggested some of the best MOPA fiber laser machines.
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MOPA Fiber Laser Technology-Explained
What is MOPA and How Does it Work?
MOPA is short for Master Oscillator Power Amplifier.
The name refers to its two gas discharge chambers, the master oscillator, and the optical amplifier.
First, the laser beam is generated at the master laser/oscillator. Then the generated laser beam is amplified or magnified by the optical power amplifier.
The amplified laser output is then sent to a galvo (mirror galvanometer) head in the MOPA laser marking machines to manipulate the laser beam's path for high-speed engraving applications.
With the help of a galvo head, laser machines can engrave at a very high speed.
As a result, Galvo heads are typically used in portable laser engravers.
In MOPA fiber lasers, the master laser source is a fiber laser, and the optical amplification is done using magnification lenses.
These lenses can make the laser beam to oscillate and amplify the laser power up to four times.
MOPA fiber laser has a variable pulse duration, which is made possible by the two gas discharge chambers.
It can be controlled to adjust the laser beam's pulse duration anywhere between 2ns - 200ns.
Applications of MOPA Laser Technology
It engraves each color separately as the laser beam produces a chemical reaction over the stainless steel material generating a superficial permanent marking.
MOPA laser marking can be used on plastic material surfaces for applications that require limited melt burns. Also, the engravings made on dark plastic with a MOPA laser are easily visible.
It can be an alternative to the expensive UV lasers used for plastic engraving.
However, it cannot be considered a cheaper alternative, MOPA is costlier than most other fiber laser engravers, which can perform descent engraving operations on plastic.
You only need to get a MOPA laser engraver if your application requires color-engraving metals and black marking anodized aluminum.
A standard fiber laser is more than enough for most other engraving applications.
MOPA Laser Engraving - Material Capability
For engraving on most soft materials, cheap and reliable laser engravers are more than enough, but for engraving effectively on metals, you need to use a fiber laser.
Fiber laser marking is ideal for almost all metals and can engrave them with a black or grey mark, whereas a MOPA fiber laser can produce colorful engraving marks on various materials.
A MOPA fiber laser can engrave on aluminum (black-engrave), brass, acrylic, nickel, carbon steel, stainless steel (color-engrave), chrome, carbide, tungsten, iron, silicon, gold, titanium, silver, other precious metals, plastic, and more.
It can deep engrave on metals with a smooth cut edge, and on plastic, it does not leave behind yellow burns.
MOPA laser also makes it easier to work on sensitive materials like gold, nickel, plastic, and Printed Circuit Boards (PCBs) that are generally a little hard to engrave using other laser machines.
The Good and Bad of MOPA Fiber Laser Technology
The major advantage of using a MOPA laser is its ability to mark colors by surface oxidation and its adjustable pulse duration.
Since the frequencies, pulse durations, and energy are adjustable in a MOPA laser, you will have much more control over the engravings.
Short duration is especially beneficial when marking on plastic materials as it provides high contrast making with low or no burns and low foaming.
The low heat development in metal parts while engraving with MOPA lasers limits corrosion and gives clean marks.
MOPA fiber laser technology also has all the advantages of a standard fiber laser.
It has high precision, low energy utilization, powerful beam quality, high-speed marking, long lifetime, is air-cooled, high optical quality, and is maintenance-free.
The major disadvantage of MOPA fiber laser technology is its high price. They are costlier than most other fiber laser engravers in the market.
MOPA also lags in the speed of engraving. The color engraving part is slower than the average speed of common fiber laser engravers.
This will be a problem if you plan to process thousands of metal pieces with color engraved logos in a single day.
Differences between MOPA and Q-switched technology
MOPA v/s Q-switched Technology
Though Q-switched and MOPA technology uses fiber lasers, their operation has fundamental differences.
Q-switching technology is sometimes referred to as "giant pulse formation" or "Q-spoiling".
Q-switched technology is used on most standard fiber lasers to produce a pulsed laser beam. It allows the laser to achieve more extreme peak powers than continuous-wave lasers.
In a Q-switched laser, such peak power is achieved by using a variable attenuator inside the laser's optical resonator.
In a Q-switched fiber laser, the pulse duration is fixed, and It can be anywhere between 80ns - 120ns.
MOPA technology uses two gas discharge chambers (i.e., the master oscillator and the optical amplifier) to control the pulse duration, and it is adjustable anywhere between 2ns - 200ns.
Also, Q-switching has a frequency range between 20kHz - 80kHz whereas MOPA can have a frequency range of 1.6 kHz - 1000 kHz.
Both these laser technology can process the same materials, but MOPA has a little advantage in processing aluminum, plastics, and stainless steel materials.
(dark color engraving)
|Aluminum oxide thin sheet
(capable of black marking)
(white and dark engraving)
(multiple color engraving)
(high melt burns)
(rough edge, yellow burns)
(low melt burns)
(smooth, no yellow burns)
(high melt burns)
(low melt burns)
Material engraving capability comparison of Q-switching and MOPA fiber laser technologies
Why is MOPA technology so expensive?
MOPA fiber laser technology is quite new to the market, and continuous research is happening to improve its efficiency and material capabilities.
To produce a laser that can operate at low and high frequencies and offer an adjustable pulse frequency mechanism it requires many sensitive internal components (optical and electrical).
All these increase the cost of developing MOPA technology. When it reaches the customer, additional fees like taxes, shipping charges, customs clearance, service fees, etc., further increase the machine's price.
Is the difference only in the color engraving?
One of the major advantages of using a MOPA laser system is its ability to color engrave on stainless steel, but this alone is not the difference between a Q-switching and MOPA.
Q-switch technology is most known as fiber laser engraving technology. It is the default configuration used in standard fiber laser engravers.
Though both these techniques look similar, it works differently inside the machine.
Q-switching only allows the power supplies to generate path light between 1 - 500kHz, but in MOPA technology, it can generate 1 - 2700kHz or more.
This large amplitude enables MOPA lasers to have different engraving results over plastic and metal materials.
Best MOPA Fiber Laser Machines
|US Stock SFX JPT M7 MOPA fiber laser
|6.8" x 6.8" (175mm x 175mm)
|2 - 500ns
|Technical Support, VCD training video
Quick summary of US Stock SFX JPT M7 MOPA fiber laser
US Stock SFX JPT M7 MOPA fiber laser machine is a 60W laser with a JPT laser source.
It is a split-type machine, so the laser source and the engraving machine come as separate modules.
The laser source module has a footprint of 17.7" x 8.2" (450mm x 210mm), and the engraver module has a footprint of 22" x 13.7" (560mm x 350mm).
SFX JPT M7 MOPA fiber laser machine has a work area of 6.8" x 6.8" (175mm x 175mm) and can engrave up to a depth of ≤0.039" (1mm).
The maximum material thickness you can house for engraving in the work area is 8.1" (206mm).
The JPT laser source used in this machine has a repetition rate frequency ranging between 1-4000kHz and a pulse duration ranging from 2ns to 500ns.
It comes with an 80mm Rotary axis which can be used to engrave on cylindrical workpieces.
The output power can be adjusted anywhere between 10% - 100%. In addition, it comes with a highspeed galvanometer which allows it to engrave at a maximum speed of 16,535 ipm (7m/s).
It can be used for applications like
- Metal surface processing, coat peeling
- Aluminum black marking
- Semi-conductor and electronics industry applications
- Marking on plastic or other sensitive materials
- Black and color marking on stainless steel
SFX sends a user manual, EZCAD3 software, and a VCD with training videos with the engraver.
They provide a 2-year warranty for this laser machine, and you can also get technical support by contacting them.
It has a marking area of 6.8 x 6.8 inches and comes with a Rotary Axis.
Pulse duration: 2-500ns
frequency range: 1-4000kHz
|10W, 20W, 30W, 50W
|LMT MOPA, IPG, SPI MOPA
|With 163 FL Lens - 10″ x 14″
With 254 FL Lens - 14″ x 10"
|24/7 Technical support
Installation, start-up, and training services
Online remote programming and troubleshooting assistance
North American and European factory-trained engineers for application and
|19 months for LMT-MOPA, 2 years for IPG and SPI laser sources
Quick summary of eCobalt MOPA fiber laser engraver
eCobalt is a MOPA fiber laser engraver from Laser Marking Technologies (LMT). It is an ideal entry-level option for MOPA engraving applications.
It is a desktop laser engraver and has an enclosed build. It has a footprint of 24″ x 25″.
With the standard 163 FL lens, you will get a marking area of 4.33″ x 4.33″, and with the optional 254 FL lens, you will get 6.89″ x 6.89″ of marking area.
The standard eCobalt machine comes with a 20W LMT-MOPA fiber source. You can also choose from optional powers of 10W, 30W, and 50W.
The LMT laser source used in the standard configuration of the eCobalt machine has a repetition rate frequency ranging 1-400kHz and a locked pulse width of ~200ns. You also have the option to choose a 0-1000kHz laser source.
With an eCobalt laser engraver, you also have the option to choose a foot pedal, fume extraction system, laser safety glass, fixture kit, pallets, software dongle (for LMT-OLP software), and docking plates.
LMT promises a crate-to-mark time of five minutes as the eCobalt laser engraver comes fully assembled.
They also provide 24/7 technical support, training, programming, troubleshooting, and operational assistance from factory-trained engineers.
For the LMT laser source, you will get a warranty period of 19 months. For IPG and SPI sources two-year warranty is provided.
LMT offers a demo facility where you can get your hands on their machines even before buying them.
|Trotec SpeedMarker Series
|20 - 100 watts MOPA
|CO₂ or Fiber laser
|9.45" x 9.45" ,7.5" x 7.5", or 12.2" x 12.2"
ebooks, FAQs, training webinars, and more.
Quick summary of Trotec SpeedMarker series of MOPA laser engravers
SpeedMarker series of laser engravers from Trotec is a good option for industrial-level laser marking applications.
They are designed to mark metals and plastics efficiently. It is available in four different sizes: SpeedMarker 100, SpeedMarker 300, SpeedMarker 700, and SpeedMarker 1300.
These machines are available with CO2 and fiber laser configurations. For utilizing the MOPA technology, you need to use a fiber laser configuration.
SpeedMarker 100 provides a footprint of 14.8" x 31.5" and has a maximum marking area of 9.45" x 9.45". Making area will depend on the lens used.
SpeedMarker 300 has a footprint of 22.1" x 33.5" and a maximum marking area of 7.5" x 7.5". Both 100 and 300 versions only have one active axis (Z-axis).
SpeedMarker 700 has a footprint of 30.7" x 37.8", a marking area of 12.2" x 12.2", and you can get a maximum work area of 24.8" x 23.6" through segmentation of the axis systems.
SpeedMarker 1300 has a footprint of 51.2" x 37.8", marking area of 12.2" x 12.2", and maximum work area of 44.1" x 25". Both 700 and 1300 models have three operational axes (X, Y, Z).
All models can be equipped with an additional rotary axis (A-axis) which can be used to engrave on cylindrical workpieces.
Trotec offers F 100, F 254, F 330, and F 420 lenses in addition to the standard F 160 lens. Changing focal length allows you to adjust the size of the marking field.
The high-performance galvanometers used in the SpeedMarker series let you mark up to 900 characters per second (cps). As a result, it increases production output and boosts efficiency.
You can select pulse duration between 4ns and 200 ns, making it easy for high-contrast marking on metal and plastic parts.
The focus finder and pilot laser options in the SpeedMarker machines will be an extra helping hand in your production process.
All functions of these machines can be controlled via the SpeedMark software provided with the machine.
For the laser source, housing, wiring, switch gears, assist pump, and other electronics, Trotec provides a 2-year warranty and a 3-months warranty for the optics.
Trotec has detailed warranty documentation on its website. They also provide learning materials through laser projects, ebooks, FAQs, training webinars, and more.
MOPA fiber laser technology is a great advancement in laser engraving.
MOPA lasers are ideal for applications requiring engraving on stainless steel, black marking aluminum, and when you need a burn-free engraving on plastic.
You can use other standard Q-switched fiber laser engravers for most other applications.
Frequently Asked Questions (FAQ)
What is the main difference between Raycus, JPT, Max, and IPG fiber sources?
The main difference between Raycus, JPT, Max, and IPG fiber laser sources is their quality, engraving result, country of origin, price, and the materials it can process. Raycus is the cheapest option and is made by Chinese manufacturers. IPG is the most expensive among them and is German-made. Other popular brands are BCF and SuperSPI.
On what materials can I color engrave with a MOPA laser?
With a MOPA laser engraver, you can effectively color-engrave only on stainless steel materials, sometimes on titanium. It is impossible to engrave colors on aluminum, gold, silver, or other metal/non-metals.
Can the MOPA laser engrave full-color images over metal?
No, the MOPA laser engraver cannot engrave full-color images over metal. You can only engrave monochrome images. Though MOPA lasers can engrave more than 16 colors, it does so separately as the laser beam produces a chemical reaction over the stainless steel material generating a superficial permanent marking. Since it is a permanent mark, the colors cannot mix to recreate a full-color picture.