High-energy lasers (HEL) have the potential to benefit a variety of military missions, particularly as weapons or as high-bandwidth communications devices. However, the massive size, weight and power requirements (SWaP) of legacy laser systems limit their use on many military platforms. Even if SWaP limitations can be overcome, turbulence manifested as density fluctuations in the atmosphere increase laser beam size at the target, further limiting laser target irradiance and effectiveness over long distances. According to Space Daily recently, DARPA’s Excalibur program successfully developed and employed a 21-element optical phased array (OPA) with each array element driven by fiber laser amplifiers. This low power array was used to precisely hit a target 7 kilometers-more than 4 miles away. iHLS – Israel Homeland Security The recent Excalibur demonstration used an ultra-fast optimization algorithm to effectively “freeze” the deeply turbulent atmosphere, and then correcting the resulting static optically aberrated atmosphere in sub-milliseconds to maximize the laser irradiance delivered to the target. The successful demonstration helps advance Excalibur’s goal of a 100-kilowatt-class laser system in a scalable, ultra-low SWaP OPA configuration compatible with existing weapon system platforms. Continued development and testing of Excalibur fiber optic laser arrays may one day lead to multi-100 kilowatt-class HELs in a package 10 times lighter and more compact than legacy high-power laser systems. Future tests aim to prove the OPA’s capabilities in even more intense environmental turbulence conditions and at higher powers. Such advances may one day offer improved reliability and performance for applications such as aircraft self-defense and ballistic missile defense. source
