In 2015, Lockheed Martin took the wraps off a 30-kW mobile laser weapon that was powerful enough to take out a truck. Now the company will deliver a new 60-kW weapon to the US Army that earlier this month set a new record by generating a single 58-kW beam. With all phases from demonstration to development completed, Lockheed will ship the combined fiber laser to the US Army Space and Missile Defense Command/Army Forces Strategic Command in Huntsville, Alabama.

Similar to the previous laser, the new 60-kW design uses spectrum beam combining technology to produce a weapon-grade laser that is destructive as well as portable and accurate. The fiber laser modules are made of an active gain medium consisting of an optical fiber doped with a rare-earth element, including erbium, ytterbium, neodymium, or others.

The optical fibers are flexible, so the laser can be thousands of meters long for greater gain, while taking up very little space because it can be coiled like a rope. The large surface-to-volume ratio means that it's easy to cool. In addition, fiber lasers are very durable and project a high-quality beam using 50 percent less electricity than an equivalent solid-state laser.

Lockheed says that the individual lasers produced by the fibers are combined into a single beam that is intense and scalable through the addition of more fiber bundles. The present laser is close to the diffraction limit. That is, it's close to the physical limit for focusing a laser on a single spot without interfering with itself, but it's still highly efficient – translating over 43 percent of the electricity fed into it into laser light.

"The inherent scalability of this beam combined laser system has allowed us to build the first 60 kW-class fiber laser for the U.S. Army," says Robert Afzal, senior fellow for Laser and Sensor Systems. "We have shown that a powerful directed energy laser is now sufficiently light-weight, low volume and reliable enough to be deployed on tactical vehicles for defensive applications on land, at sea and in the air."

Lockheed sees the new lasers as eventually leading to new systems to provide protection against swarms of drones, rockets, and mortars that would overwhelm conventional defenses.