LASER 2003: Can fibre lasers steal the show?

30 May 2003

According to many in the laser industry, fibre lasers are now a serious alternative to solid-state and carbon dioxide lasers for industrial material-processing applications. Here, we look at some of the fibre-laser vendors that will be looking to make a splash at this year's event.

From LASER 2003. World of Photonics Visitor Magazine

The boom years of optical telecoms may be long gone, but some of the technological advances of that time will be on view to LASER 2003. World of Photonics visitors in some unexpected ways.

One example of these is in the field of high-power fibre lasers, which are sure to turn a few heads in the production-engineering sector. During the telecoms boom, firms needed reliable, high-power 980 nm diode sources to pump erbium-doped fibre amplifiers (EDFAs). The technology was developed rapidly to satisfy the market's demand.

With components like EDFAs no longer so popular, these diodes are being employed in high-power fibre lasers that are finding industrial applications such as in the manufacture of car parts and medical devices.

Two show exhibitors in particular - Southampton Photonics (SPI) of the UK and IPG Photonics, US - have shifted their emphasis away from telecoms to the industrial applications of high-power fibre lasers.

On the fast track IPG was first out of the blocks with its high-power sources and is seeing them used in the automotive and medical-device industries. "The telecoms hiccup has allowed us to fast-track high-power fibre lasers," said Bill Shiner, business-development manager of IPG Photonics' industrial-laser group.

While IPG has dived straight into the market, SPI has added to its ranks senior staff with experience in the industrial sector. The firm's plan is to sell its fibre sources to OEMs, rather than direct to the user application. SPI has developed what it believes to be a superior fibre design. So far, it has focused on military applications (it has contracts with DARPA in the US and Qinetiq in the UK), but at LASER 2003. World of Photonics, SPI will be launching its first fibre-laser products tailored to the industrial market.

In a fibre laser, a doped silica fibre is excited by a diode source. Two Bragg gratings written into the fibre act like the mirrors of a "normal" laser cavity to generate the laser emission, resulting in a compact source with excellent beam quality. IPG has found a way to "bundle" its ytterbium-doped fibre lasers together efficiently, and it has produced systems that emit up to 6kW continuous-wave power at 1080nm.

Aside from the many technical advantages claimed by the makers of fibre lasers, it is their cost-of-ownership that may turn out to be the key factor. Stuart Woods is SPI's director of business development. He estimates that over the typical lifetime of a source, the total cost of ownership of a fibre laser is approximately one-third that of a similar carbon dioxide or solid-state device. This is despite the initial purchase of a fibre laser generally being slightly more expensive than a DPSS laser, and it highlights the exceptionally low maintenance cost. Woods has another way of putting it: the fibre laser gives the lowest "cost per millijoule" of any comparable laser, coming in at less than $200.

Faster welding IPG recently installed a 2kW fibre laser at the Edison Welding Institute, a leading materials-joining organization in the US, and a 6kW fibre-laser unit at an (undisclosed) automotive plant in Germany. During trials, the air-cooled 6kW unit was integrated with a robot and used for welding and cutting steel and aluminium alloys. According to IPG, the fibre laser could cut and weld faster than comparable YAG sources.

"Last year industry experts forecast that a multiyear development would be required to convince automotive and other major industries to accept this unknown technology," said Shiner, adding: "Large numbers of prospective customers are now lining up for pre-production tests."

Shiner is confident that IPG lasers will go on to make a big impact on a variety of applications: "The lasers have a 20% wallplug efficiency and are ideal for marking, cutting and welding," he said. "I believe that they will revolutionize the industrial-laser market."

Meanwhile, several SPI units are undergoing customer-evaluation tests. SPI's DARPA project is to build a singlemode, single-polarization 1kW fibre laser with an M² value of 1. The first phase of this project is now complete, with the firm producing a 50W polarization-maintained (PM) output at 1060nm and a 25W non-PM output at 1550nm. The Qinetiq contract is to produce distributed-feedback fibre lasers for acoustic sensor arrays, and the first stage of this project was completed in December last year.

SPI's fibre lasers are based on its patented fibre design. Mikhail Zervas, SPI's chief scientist, explained: "Conventional active fibres are core-doped at the centre of the fibre. Our design is based on ring doping." Zervas says that conventional doping increases saturation and limits the maximum extractable energy from the fibre. With ring doping, the gain is more controlled and the output less noisy.

With its Q-switched fibre lasers, SPI reckons that it should be able to deliver more energy per pulse than is possible with the conventional active fibre architecture.

JDS Uniphase also has plans for its fibre lasers. Product marketing manager Rüdiger Hack says that the firm is working to increase the power output: "The next step is 50 and 100W models with an M² of 1."

While Hack also believes that fibre lasers will revolutionize industrial-laser applications, he believes that costs are currently too high: "Manufacturers need to work on driving down component and manufacturing costs, especially for high-volume applications."

Shiner's view appears to dispute this: he says that the price of IPG's fibre sources are comparable with those of Nd:YAG sources up to around the 4kW mark. Any higher, and he admits that fibre lasers do become the more expensive option.

Not that this is dulling his optimism: "I think [fibre lasers] will become huge in the cutting market. I don't really see how we can lose - in a few years they should really dominate the YAG business, especially in areas like automotive welding. We will take on YAGs first and then carbon dioxide lasers."

Currently, the market - estimated to be worth $60-70 m - is dominated by IPG, which has a share of more than 50%. JDS Uniphase takes the only other significant share with 26%. This looks set to change as SPI enters the market, with other major laser vendors also expected to get in on the act.

Woods' estimate is that the total addressable market for fibre lasers could be as much as $300 m. He argues that multisource agreements between fibre-laser vendors could be the way forward.

Well, so much for the hype. At LASER 2003. World of Photonics you can see what the fibre-laser vendors have on offer.