PTB >> What's Next? Laser Technology

The highly competitive laser market continues to capture our attention with promising new technologies and emerging applications as well as the advancement of existing technology. Photonics Tech Briefs (PTB) recently discussed these issues with experts from some of the industry’s leading companies.

Fiber lasers are publicized as having the capability to displace other lasers currently used in industrial applications. How will this technology impact the marketplace?

“Fiber lasers hold great promise for a wide range of applications because they are truly solid-state with a minimum of exposed optical interfaces, have very high efficiency, and are capable of exceptional beam quality. In the near future, the most important markets they will address are micromachining, automotive, and biomedical.

The high beam quality and 1 µm wavelength means they can directly replace Nd:YAG lasers in many industrial applications, both diode and lamp pumped. The already low cost and high reliability of CO₂ lasers may limit the growth as CO₂ laser replacements, but high beam quality and the ability to both cut and weld with the same fiber laser could pose a challenge to CO₂ down the road.

Technologically, one of several challenges in building a fiber laser is how to effectively couple the pump light into the gain fiber. Single emitters address one class of coupling approach and fiber-coupled bars address another class. The choice of bar or single-emitter pump depends on the power level and ultimate performance characteristic of the fiber laser. Broadly speaking, low-power fiber lasers and some pulsed fiber laser architectures will likely use single emitters; high-power (>100 W) fiber lasers will likely use fiber-coupled bars. However, there already exist fiber laser architectures in the marketplace that break both of those guidelines.”
— Robert S. Williamson III, Ph.D., Director of Business
Development, Alfalight, Inc.

“Low-power fiber lasers (up to 50 W) have been successfully making their mark in both the coding and marking markets as well as in some specialized medical applications. However, because they emit in the 1-micron range they are generally limited to processing metals and are unlikely to be used in processing non-metals, such as plastic, paper, or textiles. These materials will remain the domain of CO₂ lasers.

More recently, fiber laser technology has shown a lot of potential in producing cost effective high-power lasers (up to 4 kW). They represent a technology threat to the established Nd:YAG and high-power CO₂ lasers, especially in the areas of metal processing. Lasers of this range are mainly used for the cutting or welding of aluminum or steel, and are anticipated to become widely deployed in the welding of automotive body parts.

While technologically they have the potential to displace some of these high-power industrial lasers, significant parts of this industry are conservative and will require a demonstration of both product cost effectiveness and the creation of a compatible service strategy.

Looking at the cost structure of fiber lasers, its easy to see that any company that wants to make high-power systems would have to produce its own laser diodes as they are such a high proportion of the product cost. If you have to buy diodes on the open market to make a fiber laser, you will not have the cost position.”
— Paul Crosby, Vice President of Marketing, Coherent Inc.

“When talking about industrial grade moderate (50-500 W CW) and high power (>500 W CW) systems, diode bars or stacks can not compete with single stripe diodes. In this case there is almost no difference between diode-pumped solidstate lasers and bar-pumped fiber lasers because the main advantages of fiber lasers — long life and absence of any bulk optic for alignment — are lost right away.

Further, fiber laser companies that buy everything from the open market (like diodes, fiber, combiners, etc.) would never be able to compete in price with solid-state laser technology. Only companies that are very vertically integrated and manufacture most of the components in house could be really successful and competitive not only to solid-state lasers, but also to CO₂ lasers.

In 1 to 2 years our prices will be able to compete with CO₂lasers. This is already happening for cutting applications. Fiber lasers will completely replace CW Nd:YAG lasers for new installations in 2 to 3 years. CO₂ lasers will compete with fiber lasers much longer due to their simplicity, very good beam property,and low cost. But, in metal cutting for example, fiber lasers have a great chance to completely win in 3- to 5-years time.”
— Dr. Denis Gapontsev, Director & Vice President of R&D, IPG Photonics

“The “Holy Grail” for fiber lasers remains the over $500M market for kW-class laser systems. Fiber lasers should provide significant advantages over CO₂ systems, disk laser systems, and lamp-pumped systems in this category. Given the advantages of fiber lasers, new laser applications can be expected to emerge over time.

Both single-emitter laser diodes and laser-diode bars may be winners, depending on the application of the fiber laser. Today, bar pumping is more cost effective for total power, whereas single emitter pumping provides greater lifetimes (especially when power cycled) and simpler thermal management. The usage pattern will depend on the power requirements, lifetime requirements, and the nature of the output (true CW or power-cycled). Most fiber laser manufacturers today use single emitters because of their proven reliability, but bar diodes seem to be making headway at the higher power levels. Still, as long as they remain close in price per watt, single emitters should continue to dominate.

I also expect to see single-emitter ensembles utilized in nonfiber laser products in the coming years. While fiber lasers pioneered the introduction of single emitters as laser pump sources, they make a lot of sense for end-pumping DPSS YAG lasers (including disk lasers) and can be used in direct diode material processing applications.”
— Andrew Leuzinger, Product Marketing – Laser, Optics, & Display Products, JDS Uniphase Corp.

“Fiber lasers will definitely have a niche. They are very efficient and effective industrial laser tools and could potentially leap frog some other industrial lasers that are out there now.

There is a healthy debate between single-emitter diodes versus diode bars to pump fiber lasers. The challenge is who will dominate. For nLight, we are well positioned to address either pump configuration as we offer both high-brightness single emitter products and high-power bars.

The benefit of bars is that your pump cavity (the amount of lasers needed) can be smaller, allowing you to make a more compact fiber laser. If you listen to IPG Photonics, bars do not yet have the same reliability as their single emitter pump sources. The fact is fiber lasers today are industrial tools. It is my opinion that end users can be satisfied with 40,000 to 50,000 hours of reliability from the pump source as opposed to the touted 500,000 hours of reliability. It seems unclear to me that telecom reliability is really needed for these types of industrial lasers.”
— Merrill Apter, Vice President of Sales & Marketing, nLight

“Initially, fiber lasers are targeting the higher-end systems, and more directly the YAG systems, but they certainly have the potential to move into any of the materials processing markets. It is going to take much higher reliability and lower cost to get there.

The cost of conventional, sealed CO₂ lasers is coming down due to better technology and larger production volumes. There is still a lot of life left in the CO₂ laser, particularly if issues with flexible beam delivery systems can be solved. That would be a tremendous step forward.

In the history of the laser business, there has always been new technology that carves out very nice niches, but the old technology is still there. Our biggest seller is still the laser we developed 20 years ago because it fits the market very well. Fiber lasers will also find areas that they fit well, but I am doubtful that they can totally obliterate the competition. In the next 3 to 5 years they will make a lot of ground, but we will be making just as much forward progress.”
— David Clarke, President, Synrad, Inc.

The potential of fiber lasers is often linked to the progress of their pump source, diode lasers. What are your goals and expectations for diode laser technology?

“Overall I believe that the diode laser is a technology seeking a solution. Some of the industrial markets have been able to use the diode laser very effectively, for example DPSS industrial via drilling laser systems or end pump DPSS laser markers and engravers. But the fact is that diode lasers in other markets and applications are still, for all intents and purposes, in the infancy stage of their product lifecycle.

Over the last 2 to 3 years I have witnessed a lot of activity around the DARPA Super High Efficiency Diode Source (SHEDS) program, almost a renaissance within the diode laser industry. The SHEDS program is causing manufacturers to go back to our roots and reengineer the laser structure itself. SHEDS type lasers have yet to be fully commercialized, but the goal is to spill this technology over into commercial products. You will see, over the next 12 to 24 months, very efficient commercial products that are very high power that can operate in true manufacturing or harsh environments. The goal of SHEDS is to make these lasers 80% efficient at elevated operating temperatures.

Along with this improved laser structure is the need to improve thermal management by packaging them on very novel, thermal platforms or heat sinks. This is a parallel path to the SHEDS activity.”
— Merrill Apter, Vice President of Sales & Marketing, nLight

“Ageneral trend right now is to improve the efficiency of diodes, which will help
people design new systems at lower costs and, at times, use fewer diodes. At the
same time it will help enable new markets. We are also working hard to improve diode reliability. Going from a lifetime of 10,000 hours now to 20,000 or 30,000 hours would reduce the cost of ownership for our customers.

We are doing this by improving all the steps in the process of building diodes. Designing a much more efficient epitaxy and process for the wafer processing, as well as the assembly of the diode on the heat sink. When you add all of those details together you can obtain very high-efficiency, high-quality products.”
— Franck Leibreich, Director of Marketing – Diode Lasers, Spectra-Physics Division of Newport Corp.

There is strong demand for lasers in biotechnology and medical applications.
How do you perceive the opportunities and challenges facing laser manufacturers in this market segment?

“The medical and biotech markets are driving a lot of the development in femtosecond (ultra-fast) laser technology for analytical instruments. People are pushing for real-time measurement and analysis of live cells, cellular components, and disease transfer properties that are critical for applications like cancer research. Ultra-fast lasers enable real-time information and the opportunity for non-invasive diagnostics with less patient downtime.

The technology is currently out there to produce these lasers, but cost is holding
the market back. System size is also cumbersome due to the size of current ultra-fast laser systems available. A good portion of the fiber laser technology can go the route of ultra-fast lasers, so it seems likely that the fiber laser manufacturers will try to address this size issue. The remaining and non-trivial issue is to get the cost down by at least an order of magnitude in order to truly expand the market.”
— Lisa Tsufura, Marketing Manager, Melles Griot Laser Group

“Life and health sciences is a very strong market because there are always new applications – more of them are laser based – and medicine is always looking for
improvement. It is not only surgery tools, but also medical diagnostic, like cell imaging, drug testing, DNA sequencing, cell sorting, and protein analysis.

You now find lasers in areas you would have never expected. A good example is cell imaging. Microscopy companies use femtosecond lasers, which just 15 years ago were monster systems limited to physics labs. Now they are hands-off, computer-controlled tools integrated into a system for confocal imaging, which basically gets information down to the sub-cellular level.

The government drives a lot of this because they provide a lot of funding for life
and health sciences, but big bio-medical companies looking for growth opportunities
also drive some of it. They want higher performance, higher reliability, and lower
cost, which is a challenge. But that is where the market is going, and we are doing
whatever we can to accommodate that.”
— Arnd Krueger, Director of Marketing, Spectra-Physics Division of Newport Corp.