NIF program benefits commercial photonics too

LIVERMORE, CA--The National Ignition Facility (NIF) laser, which is the world’s largest laser system, was recently completed--as is well known from the publicity the milestone received (see www.laserfocusworld.com/articles/355517). Less well known are the details of how the NIF laser has aided the photonics industry in general. While based at Lawrence Livermore National Laboratory (LLNL) near Silicon Valley’s concentration of photonics companies, the NIF program has drawn from businesses near and far.

“Not only is NIF the world’s highest-energy laser (it will produce nearly two megajoules of ultraviolet laser energy in a single few-nanosecond shot), it’s also the biggest and most complex optical instrument ever built,” notes Ed Moses, NIF program director. “And thus, constructing a laser facility of this size and complexity required the creation, in essence, of a whole new large high-precision optics industrial capability.”

The facility has more than 7,500 meter-sized optics and about 30,000 smaller optics--but fabricating the optics was just the beginning. NIF’s optical specifications also required state-of-the-art measurement and coating techniques and new methods for amplifying, transporting, and frequency converting the laser beams to the needed energy levels. “NIF scientists worked closely with major optics vendors including Schott North America, Hoya USA, Cleveland Crystals, Kodak, ITT, Zygo, Tinsley Laboratories, and Spectra-Physics, along with the University of Rochester’s Laboratory for Laser Energetics, to develop these technologies,” says Moses. “Our scientific and engineering team made order-of-magnitude improvements in manufacturing precision large optics, including continuous-pour glass, rapid-growth crystals, optical coatings, and new finishing techniques that can withstand the ultra-high energy of the NIF lasers.”

In addition to the NIF laser, the LLNL has constructed the Mercury laser, which is a single-beam laser system that is building on NIF’s accomplishments (see www.laserfocusworld.com/articles/355406). While the NIF laser can fire one megajoule-sized pulse every 90 minutes, the Mercury laser will fire at a sustained rate of ten 100 J shots a second. Mercury is diode-pumped, rather than flashlamp-pumped like NIF. Mercury’s beam is amplified by passing through slabs of specially grown ytterbium-strontium flouroapatite crystals, as opposed to NIF’s neodymium-doped phosphate laser glass; more advanced amplifier media, such as transparent ceramics, are also being developed.

Once the technology is developed, it can be transferred elsewhere. “NIF technology supplied the seed for other large glass-laser efforts in the U.S., including the OMEGA laser at the University of Rochester and the Z-Beamlet laser at Sandia National Laboratory in New Mexico,” says Moses. “Lasers in Japan, France, the U.K., Germany, and other countries around the world also use technology developed here. NIF research into controlling optics damage from high-energy lasers is helping scientists plan for two major inertial-confinement fusion projects now being developed--the European High Power Laser Energy Research Facility in the U.K. and the Fast Ignition Realization Experiment in Japan. The French Laser Megajoule also will use a version of the NIF optics.” And such technology is not just passed back and forth between research institutions; commercial outfits around the world are involved too.

Moses believes that the laser research going on at LLNL, both at NIF and elsewhere, will lead to the development of ultrashort-pulse lasers, high-average-power lasers, tunable gamma-ray sources and compact particle accelerators that will be used for basic science, homeland security, battlefield defense, industry, and energy security. “I think the 21st Century is going to go down in history as ‘the photon century,’” he adds. “Photonics today is where electronics was early in the last century.”