In creating a laser weapon for military use the biggest challenges for researchers are: 1) creating a laser that can reach high enough power to partially destroy or disable a target; 2) tracking numerous target objects simultaneously and 3) propagating the laser efficiently and staying focused on the target even in difficult atmospheric conditions, such as that caused by dust or humidity.
Two different approaches are in contention in the race to develop working high-energy lasers for military weapons systems: solid state lasers and fiber lasers. Generally, the active medium of a solid-state laser consists of a glass or crystalline host material to which is added a dopant such as neodymium, chromium, erbium, or ytterbium. The fiber laser is a variation of the standard solid-state laser, with the medium being a clad fiber rather than a rod, disk or slab. Laser light is emitted by a dopant in the central core of the fiber. The laser cavity in fiber lasers is constructed by fusion splicing different types of fiber.
100 kW is considered the industry benchmark and the military’s goal for high-energy laser weapons and this level has been achieved in demonstrations of solid-state laser systems. But fiber lasers typically require less power to maintain high beam quality and are more compact than other designs. In 2017 the U .S. Army plans to demonstrate a 60kW fiber-laser system developed by Lockheed Martin. After the 2017 demo, the Army plans to upgrade the system to 100kW by adding modules.
Production of the fiber modules laser is now taking place at Lockheed Martin's Bothell, Washington facility. The modular laser design allows the laser power to be varied across a wide range. The company has incorporated commercial fiber laser components in these modules to reduce production cost. The Army has the option to add more modules and increase power from 60kW to 120kW as a result of the laser's modularity.
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Lockheed Martin recently used a 30kW laser weapon, known as ATHENA (for Advanced Test High Energy Asset) to disable a truck (see photo above). The ground-based prototype system burned through the engine manifold in a matter of seconds from more than a mile away. The truck was mounted on a test platform with its engine and drive train running to simulate an operationally-relevant test scenario.