The Use of Rare Earth Elements in Fiber Lasers
Fiber lasers have emerged as one of the most versatile and cost-effective types of laser technology in the past couple of decades. Many fiber laser systems make use of rare earth elements in their construction. Understanding the advantages that this tech offers is intrinsically linked to appreciating the role that these elements play in the laser’s functionality, so let us dive into this topic and unpick it in comprehensible terms.
Which rare earth elements are used?
The rare earth element category is made up of 17 elements. What makes them trickier to harness than other elements is the fact that they are dispersed fairly broadly, which means that the process of acquiring them is often labour and energy-intensive.
When it comes to fiber lasers, the fiber inside is doped with rare earth elements, there can actually be numerous different options, depending on availability and desired functionality. Erbium is amongst the most commonly deployed in this context, although it is also possible for other elements such as neodymium, holmium, thulium, ytterbium and praseodymium to be used.
The type of element chosen may also impact the nature of the host glass used; for example, erbium can be found in silicate, phosphate and fluoride glasses, while something like ytterbium is usually limited solely to silicate glass as the host.
Why are these elements important?
Rare earth elements are harvested to be used as active ions in the construction of the glass fiber cores that help to focus the laser light in these modern manufacturing tools.
They are particularly advantageous because of the way that they absorb and fluoresce across specific portions of the spectrum, allowing them to amplify the laser pump source effectively.
All of this means that little of the useful light is lost and so fiber laser systems can be highly efficient, requiring less power than alternative gas or crystal laser solutions.
Another advantage of using rare earth elements in fiber lasers is that they offer high levels of stability and also afford additional longevity, meaning that they can survive for long periods of use without the need for any kind of maintenance or outside intervention. This further reduces operating costs and means that even with high energy output, rare earth element doped fiber lasers are resilient and reliable in the long term.
How are they integrated?
As mentioned earlier, different rare earth elements will be combined with different host glasses depending on their properties and the intended use of the resultant fiber laser. The concentration of these elements in the host glass will vary from as little as 1 part per million up to many thousands, with the higher concentrations proving most effective for use over shorter, higher-powered devices.
It is primarily within the core of the fiber laser’s construction that these elemental ions are deployed to optimise their effectiveness. Manufacturers have to strike the right balance between the concentration of elemental ions within the structure of the glass because beyond a certain point this will begin to compromise performance, which is obviously not desirable.
What are the benefits?
We have touched on some of the advantages of rare earth elements in the context of fiber lasers already but it is worth expanding on the perks they bring to the table in a practical context to truly understand why this technology is being heralded as a vital development at the moment.
The presence of the elemental ions in the core of the fiber allows the light to be focused with immense precision, creating a high-quality beam that is emitted accurately on a single point. This makes fiber lasers suitable for many applications, with additive manufacturing and ablation also joining the fray alongside the uses touched on in the opening paragraph.
The stability provided by the way the ions are integrated with the core of the host glass is also an essential benefit, since it means that fiber lasers can be set up and used without the need for complex configuration. This also means that there are no alignment issues to worry about, so while a crystal-based system might be susceptible to being compromised by an unexpected impact, resulting in costly downtime, a fiber laser will be far sturdier.
The accuracy and power efficiency of fiber lasers goes hand in hand with lessening the wear and tear on the system and reducing the need to invest even more energy in cooling the assembly during operations. The rare earth elements in the glass help convert up to 80 per cent of the input energy into laser light output, meaning very little is lost as waste heat.
The elements also help to spread the heat that is emitted during use along the length of the fiber, rather than leaving it concentrated in one particular area. This allows for even dissipation and lessens the likelihood of a specific component failing.
All of this means that fiber lasers doped with rare earth elements are well suited to deployment in industrial environments where their power, precision and resilience are all desirable.
What are the challenges?
At the moment the rare earth elements market is enjoying double-digit growth. This is fuelled not only by the rise of demand for fiber laser systems but also by the use of these materials in the production of rechargeable batteries. These are becoming required in increasingly greater numbers to create electric cars.
One issue with the way the market is configured as the moment is that China is the dominant force, supplying 95 per cent of these elements to the rest of the world. It has levied increased tariffs to manage its resources and prevent total depletion of reserves in some cases, which means that costs for these elements can fluctuate.
While this is not an issue in the short term, it does mean that there is a long term need to identify additional sources of rare earth elements so that systems which rely on them can still be made.
Call us to discuss your requirements
As a fiber laser manufacturer, we are delighted that our products are available in 150+ countries around the world. Rare earth elements present in our fiber lasers are used for a wide variety of applications, from cutting and drilling to welding and cleaning.
Why not contact our team of experts today for guidance on how fiber lasers from SPI can help your organisation? Call us or contact us online to learn more. We would leave to hear from you.
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