Navy laser weapon deployment

The U.S. Navy will deploy a high-energy laser weapon on the USS Ponce in fiscal 2014, chief of Naval Research Rear Admiral Matthew Klunder announced April 8, 2013 at the Sea-Air-Space exposition. The Navy Laser Weapon System (LaWS) will be the first high-energy laser deployed for field use by the armed services. The Navy has tested the laser system against its prime targets, moving small surface boats, and remotely piloted vehicles.

The at-sea deployment comes two years earlier than the Navy had planned. That may be a first in laser weapon development, where schedule slippage and cost overruns have been common. The New York Times reports LaWS cost just under $32 million, roughly two orders of magnitude less than the Airborne Laser, dropped from the fiscal 2011 budget after it failed to reach the required 200 km range.

NAVY LaWS on board a ship during tests of the laser weapon. (Image courtesy of the US Navy)

LaWS is part of the new generation of electrically powered solid-state laser weapons, which Navy officials say offer two advantages. One is a "deep magazine," the ability to fire pulses as long as electrical power is available--and ships have plenty of power. The other is cost. Klunder said, "Our conservative data tells us a shot of directed energy costs under $1," compared to $100,000 or more to fire a missile.

The choice of LaWS marks a big success for fiber lasers. When the Pentagon launched the Joint High Power Solid-State Laser (JHPSSL) program in 2002, developers focused on diode-pumped slab lasers, which at the time seemed the technology most likely to reach the 100 kW sought for defense against rockets, artillery, and mortars. JHPSSL reached that level in 2009, but fiber lasers have been catching up. The Naval Sea Systems Command reached 30 kW by combining the beams from six 5.5 kW industrial fiber lasers to shoot down a drone in 2010. LaWS has been upgraded since then, but Navy officials did not disclose the output power of the current system.

The laser is not the only challenge. For the current version of LaWS, L-3 Integrated Optical Systems (Pittsburgh, PA) upgraded the pointing and tracking system, improving accuracy of the fine steering mirror and controls, and improving the software and user interface. "We took scientists out of the loop to make it operable by seamen," said Don Linnell, director of business development and strategy. The Navy considers that a must for fielding laser weapons.

IEEE recognizes fiber laser milestone

Fiber lasers and amplifiers can do incredible things, but the technology is not as new as you think. Half a century ago, Elias Snitzer and a handful of colleagues at the American Optical Company's Research Center in Southbridge, MA pioneered both technologies. On October 26, 2012, I attended the dedication of plaque recognizing the achievement as a Milestone in electrical technology by the Institute of Electrical and Electronics Engineers.

Founded in the 19th century to make spectacles, American Optical in 1954 became the first company to try to develop practical fiber-optic imaging bundles, which were first demonstrated by academics and an independent inventor working on shoestring budgets. Initially funded by the Central Intelligence Agency to develop image scrambling bundles for secure messaging, AO later developed imaging bundles.

AO hired Snitzer to work on fiber optics in 1959. At his job interview, he recognized the puzzling patterns in a fiber bundle as evidence of lateral modes, and later published the first analysis of single-mode transmission. Interested in the laser, Snitzer took advantage of AO's glass expertise to make a solid-state laser of glass rather than crystals. He formed barium crown glass doped with 2% neodymium oxide into a three-inch rod thinner than a millimeter, covered with a low-index glass cladding to improve light transmission.  Pumping with a coiled flashlamp like the one Theodore Maiman used in the ruby laser, Snitzer demonstrated pulsed lasing in the stiff neodymium-doped fiber at room temperature in 1961.

In 1963, Snitzer and Charles Koester amplified pulses by up to a factor of 50,000 in a meter-long fiber laser without reflective end coatings, coiled around a linear flashlamp. Their goal was to measure gain dynamics, but the demonstration also showed the potential of fiber amplifiers.

The lack of good pump diodes kept fiber lasers and amplifiers from being practical until the 1980s. Snitzer played an important role in that development, developing doped fiber sensors, demonstrating 1480 nm diode pumping for erbium-fiber amplifiers and developing dual-core fibers now used in high-power fiber lasers. Snitzer died in May, but lived to see developments including multi-kilowatt fiber lasers and high-speed communications through fiber amplifiers in the global telecommunications network. Four of his children who attended the Milestone dedication were pleased by the recognition of the man they knew as "dad."

IEEE Milestone for fiber lasers and amplifiers, across the street from former American Optical headquarters in Southbridge, MA. (Courtesy of Dick Whitney)