Pumping up the power

17 Jul 2003

Thanks to a boost in their output power, fibre lasers could soon challenge diode-pumped Nd:YAGs as the source of choice for materials processing tasks. Oliver Graydon spoke to Southampton Photonics about its new range of products and its move away from telecoms.

From Opto & Laser Europe July/August 2003

The launch of a range of powerful fibre lasers for industrial applications at the LASER 2003 show in Germany last month marked a U-turn in strategy for Southampton Photonics Inc (SPI), UK. The start-up was founded in early 2000 to exploit the pool of optical communications expertise that existed at Southampton University's Optoelectronics Research Centre (ORC). However, the dramatic collapse of the telecoms market since then has forced the company to radically rethink its positioning.

In a distinct shift away from its original business model, which was based on a strong optical communications market, SPI expects its new series of 100 W continuous-wave (CW) and 25 kW 1mJ pulsed ytterbium-doped fibre lasers to bring in revenue from materials processing markets such as printing, marking and engraving.

"For all practical purposes we're launching a new company," admitted Stuart Woods, SPI's director of business development. According to Woods, the company might have started out on a different footing in the first place, had telecoms not seemed such an attractive proposition in 2000. "We would have probably pursued a path very similar to IPG Photonics [a maker of industrial fibre lasers] two or three years ago, and would have been on a completely different trajectory," he said.

Boom and bust When the telecoms boom was at its peak, it was a business proposition that looked as though it couldn't fail: SPI would use the ORC's leading-edge research in optical fibre technology to develop a range of laser sources, filters and optical amplifiers. These would help communications networks to handle ever-increasing data capacities.

In June 2000 David Payne, director of the ORC and SPI's founder and chairman, and Don Spalinger, a US entrepreneur and SPI's then president, closed an enormous first-round funding deal of $55m (€48m). Several US and European investors, including Sevin Rosen Funds, Interwest Partners and Amadeus Capital, injected capital into the firm.

With the cash on board and a new $10m fibre-production facility being built in Southampton, things were looking good for SPI. It confidently predicted that by end of 2002 it would be employing around 500 staff and would have opened a design, production and sales facility in California.

Over the next 18 months, business continued to go well. The firm released a range of telecoms products featuring distributed feedback fibre lasers, Bragg grating filters and broadband erbium-doped fibre amplifiers (EDFAs). Then, in the middle of 2001, disaster struck. The telecoms market crashed in spectacular fashion. As the demand for optical components dried up, SPI, like many telecoms start-ups, began looking for new sources of revenue.

Kilowatt project In the autumn of 2001 SPI got involved with a US government project to develop a 1kW singlemode fibre laser. According to Woods, the seeds of the shift in SPI's strategy were sewn at this time. "That's what spurred us last year to look at restructuring the company," he explained.

The process was accelerated in April 2002 when David Parker was brought on board as SPI's new chief executive. Parker, a well known player in the world of telecoms and an expert at growing the value of high-tech firms, joined SPI shortly after negotiating the sale of Marconi Optical Components to Bookham for $28.7m. With his appointment the search for alternative applications for SPI's technology commenced in earnest.

The company decided to start using its technology to develop higher-power fibre lasers for materials processing and scientific applications. SPI's staff of around 60 people spent the rest of 2002 developing prototype devices and talking to potential customers.

As its first high-power fibre lasers were nearing the end of their development cycle this spring, SPI brought two sales veterans of the materials processing world on board to help it penetrate the industrial markets. Michael Duka from Rofin Sinar joined SPI as its director of European sales, and Ben Bramhall, previously at Coherent, was appointed to boost SPI's US sales operation.

The early results of the firm's refocus were revealed at last month's biennial LASER show in Munich, Germany, where SPI launched its new high-power fibre lasers. The initial range consists of three product families - a 100 W CW fibre laser for printing and materials processing; a pulsed 25 kW peak-power fibre laser that delivers 1 mJ 40 ns pulses; and a family of lower-power modulated versions (30 W or less) for scientific applications.

"To the best of our knowledge the 25 kW laser delivers the highest pulse energy - 1 mJ - of any fibre laser to date," said Woods. "We also have a roadmap to double this with a 50 kW version. The idea is that we're giving original equipment manufacturers [OEMs] access to different elements of the technology to suit different markets. All three products have received direct interest from customers." The first units are now going into production and SPI is currently accepting orders, with shipments commencing this autumn.

SPI's new business model consists of more than simply changing its product focus. "The key is that we are not going after the end-user market," said Woods. We are going to partner with OEMs and provide them with subsystems so that they can incorporate fibre-laser technology into their products. The likes of Rofin, Coherent and Trumpf are not going to spend $20m or so on fibre drawing towers and the research associated with it."

Telecoms technology Although the telecoms market did not bring SPI the riches it had hoped for, telecoms did accelerate the development of technology that led to the creation of high-power fibre lasers. For a start, this means that high-quality 980 nm pump diodes are now readily available and affordable.

The telecoms market also helped to spur on development of speciality-doped optical fibres with improved output powers, as well as high-performance fibre Bragg gratings.

And this is where SPI's key technology and intellectual property lies. Not only has it built a foundry that can fabricate customized high-performance gratings, but it has also developed a range of optical fibres that have a specially adapted geometry.

The first adaptation SPI has made is in its ring-doped fibre, in which the ytterbium is doped not into the central core of the optical fibre as in the traditional method, but into an annular ring that surrounds the core. This geometry improves the pump absorption and efficiency of the laser. It also reduces saturation effects, allowing a singlemode laser to be scaled up to high output powers of several hundred watts.

The second innovation is in the cladding-pumped design of the fibre. A large secondary "core" is used to guide the pump light and efficiently transfer it to the ytterbium dopant. Because this core is bigger than the traditionally small core of singlemode fibres, it enables the use of far more powerful multimode pump diodes.

According to Woods, the new range of commercial fibre lasers from SPI makes use of both cladding-pumped and ring-doped fibres to create efficient devices that may be power-scaled in the future. SPI hopes to have devices that emit at least 1 kW within the next 12 months.

That said, it still has a long way to go to catch up with IPG Photonics, which leads the fibre-laser field. It has recently released a commercial 10 kW CW fibre laser and sold a 6 kW version to an automotive plant in Germany. Nevertheless, SPI is no doubt relieved to have found a new use for its technology that looks likely to keep the company afloat, unlike so many other telecoms start-ups.