High-energy lasers await Pentagon ‘green light’

March 14, 2023
During Laser Focus World’s Executive Forum, a panel of laser experts discussed how far high-energy laser technology has come and the challenges that remain.

The U.S. Strategic Defense Initiative, aka “Star Wars program,” of the 1980s was a high-energy laser missile defense system proposed for countering intercontinental ballistic missile (ICBM) attacks. Fast-forward to 2023: The threat landscape has evolved to include small, cheap drone attacks or swarms of them, larger drones, and even hypersonic missiles. High-energy lasers may—at long last!—get their chance to shine as a countermeasure or counter-countermeasure to these threats (see video).

Small drones can be readily “purchased on Amazon for under $1000,” says Robert Walker, vice president of strategy and business development for Leonardo Electronics U.S. “They’re quite useful for intelligence, surveillance, reconnaissance (ISR) and dropping explosives on targets—they’re commonly used today in the war on Ukraine.”

Then there are “suicide drones,” which cost in the range of $20,000 to $30,000, and can be bought from Iran fairly easily. “This type of drone is also being used in Ukraine, and countermeasures available today—ground-to-air or air-to-air—cost hundreds of thousands to even millions of dollars per interceptor,” says Walker. “There’s quite an imbalance countering some of these threats.”

And way down at the other end of the spectrum: Hypersonic missiles. “While they aren’t new, hypersonic missiles are maneuverable at Mach 5, which makes it difficult to protect against them—it’s a significant threat,” says Walker. “To protect against something like this, you need something going as fast and as maneuverable. This is an interesting challenge because light is pretty fast, right?”

The U.S. currently “invests about $1 billion/year in directed-energy technology,” Walker adds. “The compound annual growth rate between now and 2030 is expected to be on the order of 18 to 20%.”

Is now the time for high-energy lasers?

The Strategic Defense Initiative era drove a lot of dreams for high-energy lasers. While it hasn’t gone away, there’s been a clear mismatch between the mission and the technology.

“It started coming together about five to 10 years ago,” says Robert Afzal, senior fellow at Lockheed Martin. “This was after backing off from trying to defeat ballistic reentry vehicles or ballistic missiles, and moving more toward threats like unmanned aerial vehicles (UAVs), lower-cost swarming threats at shorter range.”

One of the core enabling advancements of directed-energy lasers was the development of a high-power fiber laser for telecom and cutting and welding applications—which improves every year. “Defense folks leveraged the fiber laser to scale high-power lasers that are efficient with high-bream quality,” says Afzal.

Then all of the technology pieces finally came together “and the mission got easier,” he adds. “We saw a growth in applications and demonstrations from the U.S. Army, Navy, Air Force, international armies, navies, and air forces as well—all leveraging these core technologies.”

Today, applications are evolving and demonstrations are showing off the capabilities of directed-energy lasers. “But we’re still waiting to see how the customer set will adopt the technology,” Afzal says. “Are they willing to go forward and change their force structures and buy this equipment? This is the big question.”

Fiber lasers and other options

Fiber laser technology is “clearly winning today,” says Jay W. Dawson, National Ignition Facility & Photon Science Directorate for Lawrence Livermore National Laboratory (LLNL). “Beam-combined systems have done extremely well, are getting out into the field, and becoming efficient.”

But other options are being explored for directed energy. LLNL, for example, is currently working on a diode-pumped alkali laser, which Dawson believes will scale very high average powers and provide advantages of its own. “It’s far enough along, we’re ready to transition it to industry,” he says.

Another option, Dawson notes, is a distributed gain system from General Atomics, which is making inroads within the U.S. Department of Defense.

Direct diodes are also being explored as another future option. “But there will be technical challenges in terms of being able to combine diodes into a single beam,” Dawson says. “It’ll be much more difficult to coherently or spectrally combine these than it is with a fiber laser.”

Supply chain concerns

The supply chain for directed-energy lasers is a big concern—especially as directed-energy technology moves from the science and technology (S&T) phase into production.

“We’re always struggling with the demand signal,” says Michael Hofle, senior director of high-energy lasers for Raytheon Intelligence and Space. “In defense, we have many producers and one customer. Lead times are extreme, and the supply base is small. The real question here is the demand because the path to making directed-energy lasers more producible, reliable, and cheaper is quantity.”

And the supply chain robustness “isn’t tested yet,” says Prabhu Thiagarajan, senior vice president of Leonardo Electronics U.S. “We’re building small quantities so it’s okay right now, but when we need to go into production we’ll see how the supply chain holds together—from a cost point as well.”

Another concern from a components and perhaps subsystems perspective, Thiagarajan points out, is that taking S&T to production can be akin to heading into a valley of death. “How do you bridge this gap if you’re a mid- or small-size company? They typically don’t have access to the capital large-size companies have, so there need to be mechanisms to help them bridge the S&T phase and production.”

A robust demand signal “helps with access to capital markets, not necessarily for small companies, but perhaps it helps the large companies and flows down to the small companies,” Thiagarajan adds. “So that’s a real issue—a lot of critical technologies come out of small companies, but without funding to bridge that gap this capability goes away—you’re not ready when you’re ready to produce parts.”

Where’s the talent?

Finding talent—employees—is always a concern for defense contractors, and many people within the photonics realm with directed-energy expertise are approaching retirement.

“Retention of talent is going to be the next big impediment to this evolution of technology,” says Thiagarajan. “We’re starting to see it right now and need to connect with students or fresh talent at the high school level to get them interested in the technology.”

Directed-energy lasers are ready to roll

The bottom line is that the use of a laser on the battlefield is completely new and the Pentagon needs to figure out how to integrate these systems into systems they already have, and then train people about the rules of engagement and how to use them.

Directed-energy laser technology is ready to roll. It’s been demonstrated again and again at various power levels and conditions. The next big step: Doing it at rate with big orders.

About the Author

Sally Cole Johnson | Senior Technical Editor

Sally Cole Johnson has worked as a writer for over 20 years, covering physics, semiconductors, electronics, quantum, the Internet of Things (IoT), optics, photonics, high-performance computing, IT networking and security, neuroscience, and military embedded systems. She served as an associate editor for Laser Focus World in the early 2000s, and rejoined the editorial team as senior technical editor in January 2022.

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