Commercially available ultrafast-pulse lasers: An update

Lower cost per watt and more acquisitions drive growth

The field of ultrafast-pulse (UFP) lasers has seen a lot of activity in the past year since ILS first published the tables in the July/August 2013 issue. Many new players have entered the game, the cost per watt of output power has gone down, and there has been some market consolidation through acquisitions. Updated tables of commercially available lasers are presented, along with appropriate commentary.

In preparation of this article, all of the companies participating in the 2013 tally were contacted and asked for status updates. In addition, many companies were asked to participate who were either left off of last year's list, did not choose to participate, or simply did not offer UFP lasers. This list is more complete, but it is by no means a complete survey. The tables are divided into picosecond and femtosecond; placement in the tables was done by the vendors themselves.

Picosecond lasers

TABLE 1 shows 14 vendors of picosecond lasers—up from nine last year. The fundamental wavelength is still most commonly 1030 or 1064nm. Powers up to 100W are commercially available from several different vendors, with higher powers possible using Innoslab technology. Most of the responders indicated at least the availability of the second and third harmonics. There has been industry consolidation, notably with JDSU buying Time-Bandwidth and EO Technics buying PowerLase. Another very interesting note is that there has been some "crossover"—last year, all of the vendors identified themselves as being either a picosecond or a femtosecond laser vendor, but in the current tables, a number of companies (SP, Amphos, EdgeWave, Rofin, and Trumpf) are now identifying themselves as being both picosecond and femtosecond laser suppliers.

Some general comments on picosecond lasers can be made. First, pulse lengths between about 50ps and 1ns do not seem to be very useful industrially unless in very specific circumstances. Second, at even 10ps pulse length, there is almost always a difference in the processed part quality for most materials. Third, for most UFP applications, picosecond pulses are "good enough," as picosecond photons cost less than femtosecond photons and picosecond lasers are available in much higher powers. The really HOT market for high-power picosecond lasers is in sapphire processing and this is consuming most of the higher power lasers being manufactured. However, aggressive deliveries for large numbers of lasers assure that only larger companies can get into this market.

Femtosecond lasers

TABLE 2 shows 12 vendors of femtosecond lasers, representing an increase from nine last year. Only three vendors list lasers with the fundamental output over 50W. An interesting note is that Raydiance lists future plans to go to 1030nm (instead of 1553nm) in order to provide higher harmonics. At 300fs pulse length, there is little difference in the processing quality between the fundamental wavelength and higher harmonics for most materials, but materials like organics and glass do show a notable difference. In particular, metals can be cleanly processed with the fundamental output. However, if you require a small spot on target, ultraviolet (UV) photons may be necessary, even in the femtosecond regime. How short do we really need to go? The answer is that for most applications, there is no need to go below a 150fs pulse length because you have only marginal gains in part quality, but the optics—because of spectrum broadening—become much more challenging. Even though femtosecond photons usually do give a cleaner cut on target, picosecond is still good enough for most applications. Finally, air breakdown is a problem with very short pulses focused to a small spot, so beam deliveries may need to be purged.

Another important point is that most of these lasers have oscillators that run at very high repetition rates and then pulse pickers are used to send a string of pulses, usually in the kilohertz repetition rate regime, to the amplifier. However, it is also possible to send a "burst" of pulses so that instead of one pulse, a number of them come out in very short time intervals. Traditionally, the first pulse is the strongest and then the intensity of the trailing pulses declines. However, the Flex Burst mode offered by JDSU allows control of each individual pulse and the ability to tailor intensity of the pulse train individually if desired. Finally, it is also possible to tailor each pulse (SP Pulse on Demand) so that the peak intensity occurs at the beginning, middle, or end of the pulse. In any case, it is very important that the pulse is clean with a well-defined rise and fall time and also with no amplified stimulated emission (ASE).

The lasers appearing in these tables are all considered "industrial" in the sense that they are packaged appropriately for a manufacturing environment. They also have at least 50mJ per pulse for picosecond lasers and 25 for femtosecond lasers. The repetition rates must be usable, which usually means about 100kHz to 1MHz in repetition rate. There are at least 13 other laser vendors that did not get onto the tables either because they did not answer the survey, they were viewed as more "scientific," or they were just starting to manufacture UFP lasers. The most notable among these is IPG Photonics, who has been talking about having a UFP laser—but it has not been possible to actually see one! In both tables, the cost per watt of power is being driven lower and, from a well-placed IPG source, the comment was, "If you think the price of picosecond lasers is low now, you ain't seen nothing yet!" As a very general statement, the current state is such that picosecond lasers are about 6X more expensive to buy than nanosecond lasers, while femtosecond lasers are about 10X more for the same output power levels.

Summary

There are new players in the market space, there has been some consolidation through acquisitions, and there is a lot of crossover, but the general direction is providing more photons/dollar in a smaller package with higher harmonics available. As picosecond lasers become cost-competitive with nanosecond lasers, they will start to take over market share. However, you can spend an enormous amount of money on the fanciest laser, but how the laser is used and how the photons are delivered to the target make a world of difference in part quality. In particular, picosecond lasers are about to plateau on "technology maturity," as there are a lot of players and little differentiation in product specifications. The good news is that the "market maturity" is still in the beginning so that new applications and price reduction will mean that large numbers of lasers will be sold.

ACKNOWLEDGEMENTS

Thanks to all of the companies listed and the individuals who were kind enough to send me both technical information on their products and lots of figures, not all of which were used.

RONALD D. SCHAEFFER, Ph.D., is CEO at PhotoMachining, Inc. He is also a member of the Industrial Laser Solutions editorial advisory board and a frequent contributor to the magazine. His blog can be found on the ILS website.