The Air Force's Self-Protect High-Energy Laser Demonstrator, or SHiELD, was constructed to answer the call for a directed-energy weapon that could be used to protect aircraft from surface-to-air and air-to-air missiles.
Directed energy weapons can take several forms, including microwaves or electromagnetics, but the requisite use of lasers for targeting missiles seems to reinforce both a legacy preference for the technology as well as potential future applications.
SHiELD recently passed a significant test when a ground-based unit was able to eliminate multiple missiles fired from the air during an exercise at White Sands Missile Range in New Mexico. The system is still considered a proof-of-concept asset, as SHiELD hopes the final weapon will be smaller, lighter, and more durable. These specific goals seem to point to additional applications that potentially go beyond a system that fires from the ground.
According to a report from Business Insider, the Air Force has previously suggested that a laser-based missile defense weapon system could be used by a number of aircraft, from jet fighters and bombers to fuel tankers and transport planes.
Essentially, any aircraft operating in high-risk environments that are defending or carrying high-value assets could benefit from such a system due to its accuracy and one-shot power. Despite the promise of the recent test, multiple reports suggest that the Air Force is still a few years away from what it considers a fully functional prototype.