Pulsed Fiber Lasers – An Overview White Paper

The laser celebrated its 50th year anniversary back in 2010, so it’s fair to say that it’s still a relatively new piece of technology. However, it has come a long way since its founding in 1960, with multiple types of lasers being developed and it is becoming a staple part of many industries around the world. Below we explore this history in greater depth, as well as the history of the fiber laser and the pulsed laser.

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Lasers have developed to have many uses

The history of the laser

Although the term ‘laser’ has become somewhat immortalised in fiction thanks to many Hollywood blockbuster films, it’s actually an acronym that stands for “light amplification by stimulated emission of radiation”.

The meaning of the word has never changed, but the way in which the light has been amplified has. The very first laser, invented in 1960, was a uranium laser discovered by the IBM Thomas J. Watson Research Center. It was in the same year, at Bell Labs, that the helium-neon (HeNe) laser was discovered, which was the first laser to be able to generate a continuous light beam at 1.15 μm.

There were developments almost every year from then until the late 1980s, and some were highly significant. The first crystal laser, using yttrium aluminium garnet (YAG) was reported in 1962 by the same Bell Labs, and then a breakthrough was made with fiber optics in 1966. However, it wasn’t until 1977 that the first commercial installation of a communication system using fiber optics was seen.

However, this paved the way for the future of fiber lasers, and it was in 1987 that a research team from the University of Southampton announced the first fiber laser, which used erbium-doped fiber as their medium.

The other main type of laser and the most commonly used on the market today is the CO2 laser, which was invented in 1964. However, with the fiber laser being newer, it offers  numerous unique advantages over this type of system.

The pulsed laser

Each of the lasers touched on above are capable of performing the pulsed laser process, but the results that are produced are different. A pulsed beam is often chosen for several processes over a continuous wave beam as it is capable of higher peak power within a short pulse. Pulsed lasers are one of the two types of laser that we manufacture here at SPI Lasers, with our continuous wave fiber lasers being the other range.

Dr. Gerard Mourou, a University of Michigan professor, was the first person to recognise that in some cases a short pulse can deliver better results with a less heat-affected zone (HAZ) than longer pulses. In the early 1990s, his research group become the first to develop the level of peak power that was needed in ultrashort pulses to ablate materials. Ultrafast pulsed lasers were recognised for their importance as early as 1995, and have become a crucial part of the medical sector.

These ultrashort pulses are different from other micromachining processes and are used for a higher yield when it comes to the separation of atoms from a solid. Historically, it has been easy to achieve short pulses, but the challenge has been with scalability when it comes to energy or average power. The use of single-crystal fiber lasers has helped to address this, which combines both fiber and crystal, and is used to achieve a higher level of peak power.

Developments are constantly arising with pulsed lasers, and just recently a team of scientists have generated an ultrashort laser pulse using optical fiber, through a method that was previously thought as impossible. You can read more on this here.

A pulsed laser emits light in the form of optical pulses, usually nanosecond pulses. The pulse duration, energy, repetition rate and wavelength can vary depending on the user’s needs for the requirements of the task.

Some lasers emit a pulse simply because they cannot emit a continuous wave beam, while in other cases a pulsed beam is specifically required. Often, a single pulse from this type of laser can have a higher peak power than that of a continuous wave beam, making it more advantageous in some situations.

A pulsed laser beam can be delivered by several types of laser, such as gas or fiber.

The use of pulsed lasers at SPI

Pulsed lasers have been a key product of ours for many years, and with a versatile and adaptable range, have offered our clients numerous benefits and processes. With over 15 different processes available between our range of pulsed lasers, they have become important manufacturing tools in many industries around the world.

These are just some of the industries that you will find a pulsed laser is used in:

Laser drilling can create highly accurate holes

Laser drilling can create highly accurate holes

What processes can it perform?

Our pulsed fiber lasers have become some of the most reliable and powerful beam sources on the market, gaining worldwide usage across a huge range of industries. Their capability to work with a variety of different materials in numerous settings has seen them utilised for dozens of applications.

Below we’ve explored just some of these applications.

Not every single pulsed laser will be able to perform all of the above, and it’s important to think about the processes that you will need to complete before making any purchases. You can see the capabilities of our fiber lasers in our product data sheet here.

What materials can a pulsed laser work with?

Given this huge range of benefits and the number of processes that can be completed using a pulsed laser, it is capable of working with a range of materials. This includes, but is not limited to:

  • Anodised / Painted surfaces
  • Ceramics
  • Composites
  • Metals and precious metals
  • Painted surfaces
  • Plastics
  • Gemstones and
  • Thin films
Pulsed lasers are used in many industries, such as the automotive sector

Pulsed lasers are used in many industries, such as the automotive sector

Pulsed fiber lasers have been crucial in the development of many of these industries from what they were historically, to where they are today. It’s clear that they will continue to play a part in the future of these industries, and will represent a vital piece of their history moving forward!

Benefits of using a pulsed laser

A pulsed fiber laser is used to deliver a laser beam in pulses, rather than as one continuous wave. What are the benefits of our pulsed lasers that can be applied to so many applications?

1)    Flexible

Pulsed lasers are very flexible and are used for a wide variety of purposes as explained previously

2)    Material protection

It is a non-contact process, meaning that they won’t damage the material they are working with. This protects both the operative and the material itself.

This also means there are no parts to wear out (e.g. drill bits and cutting blades). This saves money in both reduced manufacturing downtime and the costs associated with buying parts.

3)    Micro-machining

With pulsed nanosecond technology, our lasers can work at a micro-level, infact even smaller than the “naked eye” can see.

4)    Versatile

They can work at up to 40 different waveforms offering pulse durations from 3ns – 2000ns.

5)    No maintenance

We’ve taken great care with the design of our pulsed lasers, and for this reason, they offer a completely maintenance-free life over an extended number of years. Using ‘Fit & Forget’ technology, you can simply focus on the output, rather than any maintenance schedules.

A practical example of this is CO2 lasers, which have mirrors in them, which need to be kept clean and aligned. Whereas, with fiber lasers the laser beam is delivered to the work piece by fiber. Therefore, the maintenance requirement and cost associated with CO2 lasers is removed.

What are the benefits of using a fiber laser?

There is more than one type of laser that is capable of pulsed bursts, but here at SPI Lasers we only manufacture fiber lasers. As the newest type of laser process to the market, we believe that it offers users the greatest array of benefits, versatility and cost when compared to the other laser processes available.

For example, when compared to gas lasers, fiber lasers require little to no maintenance, have higher electrical efficiency and can work with reflective metals without the worry of back reflection damage.

Pulsed Laser Glossary of Terms

There are many terms, definitions and phrases used in the fiber laser and pulsed laser market. Below we provide a handy glossary for any related terms that you may need. You’ll find terms specific to SPI Lasers, as well as general terms relating to the market.

Looking for more information about fiber lasers? You’ll find everything you need below

Looking for more information about fiber lasers? You’ll find everything you need below

1)    Ablation

The process where a surface layer of a material, typically a solid, is removed. This includes working with a variety of materials such as metals, plastics or composite materials.

2)    Anodised surface

An anodised surface upon a material that provides a durable, corrosion-resistant surface. It is typically decorative in nature.

3)    Cleaning

The process whereby the surface layer of a material is cleaned or prepared. Similar to ablation, this process involves the cleaning or preparation of a particular surface.

4)    Colour marking

Colour marking is one of the most popular uses for pulsed lasers. The same as marking, except a permanent colour mark is left. This can be used to enhance the aesthetic appeal of an item.

Colour marking can be used on multiple metals, as well as plastics (with the addition of inks), making it versatile enough to work with the majority of products.

It may be used to add a finishing touch to a product with something like decorative borders, to enhance the final quality of an item, or to make it stand out from the rest of the material around.

Colour marking can work with thin or thick materials and multiple surfaces. This type of application is most commonly used in the consumer goods sector, such as with the crafting of metalwork for jewellery.

You can see an example of this here: Ornamental colour laser marking of metals.

5)    Engraving

A process which leaves a permanent engraving within a material. This can be completed at both a deep or thin level. Deep engraving is commonly used for producing items such as moulds, plaques and trophies.

This process is popular for a variety of uses, such as engraving of jewellery.

A pulsed laser can be used to engrave jewellery

A pulsed laser can be used to engrave jewellery

6)    EP series (extended performance)

The most versatile source of fiber laser in the SPI EP series has up to 40 PulseTune waveforms. This provides the flexibility to vary pulse duration to maintain peak power performance over a greater repletion frequency range.

7)    Fiber laser

A fiber laser is a type of laser which uses optical fiber, doped in elements such as erbium, neodymium, dysprosium or ytterbium, as its active gain medium.

8)    HS series (high spec)

A type of laser functionality from SPI Lasers. Has variable pulse width, enhanced controls and benefits from PulseTune technology.

9)    H type

A high mode setup which offers a high pulse energy and peak power, as well as larger spots.

10)     L type

A low mode laser used for general marking applications. Has a larger spot size, and is, therefore, better for processes that will leave marks visible to the naked eye.

11)     Marking

Marking is an extremely common application for pulsed fiber lasers and finds use in many industries such as aerospace, automotive, electronics and the medical sector. It is used to leave a permanent mark perhaps in the form of a barcode, or guidance to the consumer by showing a ‘best before’ date.

12)    Micro-machining

A process which fabricates 3D and 2D structures at a micro-level. A process where micron-level tolerances and only the highest level of quality are needed, something which a pulsed fiber laser is perfect for.

13)     Nanosecond

A one thousand-millionth of a second, which is the region that our pulse durations operate within.

14)     Night and day marking

This is marking that is used to leave a permanent mark that can be visible in both the night (when backlit) and day. Used for items such as buttons on car dashboards. Industries which use this functionality frequently are the automotive and consumer electronics sectors.

15)     Precision cutting

The cutting of a material, but with ultimate precision. Often performed at a small-scale level, to create items such as lenses or medical stents.

16)     Pulsed laser

A pulsed laser refers to a laser which delivers its beam in pulses of a set duration, as defined by the user.

17)     RM series (reduced mode)

A type of laser functionality. Entry-level products with basic software and hardware.

Night and day marking is used for car dashboards

Night and day marking is used for car dashboards

18)    Scribing

Pulsed lasers can be used to scribe messages into materials such as plastics or metals, commonly used for applications such as serial numbers or identification numbers.

19)     Solar cell processing

This is the manufacture and processing of fragile silicon solar cells.

The solar industry benefits extensively from the use of pulsed lasers

The solar industry benefits extensively from the use of pulsed lasers

20)    S type

A single mode setup delivering a very fine spot size. Best suited for applications with small feature sizes.

21)     Thin film patterning

A process used to produce small features, or to isolate a specific region, on devices through the use of patterns.

22)     Thin film removal

Thin film removal is a delicate and highly precise process, which is why the versatility of a pulsed laser is so useful. It can take thin films off of the surfaces of materials such as ceramics, glass, metals or plastics, and finds uses in the manufacturing of items such as plasma displays for TVs in the electronics industry or solar cells for the solar industry.

23)     Welding

The process of welding together two or more materials. The metals can be the same, or dissimilar in nature.

24)     Z type

A laser type that delivers high peak power and pulse energy, along with a good depth of focus.

These carabiners feature an anodised surface

These carabiners feature an anodised surface

The pulsed lasers on offer at SPI Lasers

Here at SPI Lasers, we manufacture the redENERGY G4 Pulsed Fiber Laser. This comes in a range of 20W-250W, and we produce an S Type, Z Type, L Type and H Type; all capable of performing a range of processes.

As an OEM, we manufacture this laser, which is then incorporated into thousands of other laser setups and machines around the world. The benefits that we offer with our pulsed lasers are:

  • Flexibility
  • Innovative technology
  • Versatile
  • No maintenance and
  • ‘Fit & forget’ technology

A pulsed laser beam can be emitted by several different types of laser, but here at SPI Lasers we only manufacture fiber lasers. We have chosen to do this due to the range of benefits that it offers users over other types of laser process.

The benefits of fiber lasers over other types of laser are:

  • There are no mirrors or moving parts used within the light-generating source, which reduces maintenance and operating costs and requirements
  • It has a high level of electrical efficiency, which also helps to reduce the running costs. For example, a fiber laser with a power output of 3 kW uses only one-third of the power of a 4 kW CO2 laser
  • It can cut reflective metals without the worry of damaging back reflections being bounced back into the laser source

Looking for more information?

As you can see from the above information, fiber lasers have a huge usage in the modern-day world, from heavy industrial settings to smaller use. A single fiber laser setup can be used for multiple applications, making it one of the most cost-effective solutions for businesses today.

If you would like more information on pulsed lasers, please:

 

Image Credits: kpr2Ralph Gnonlonfoun, dietmaha, Tero Vesalainen, Wikimedia, Photo Mix, Mike and Mr Ganso

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