Excalibur Prototype Extends Reach of High-Energy Lasers

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.

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. The OPA used in these experiments consisted of three identical clusters of seven tightly packed fiber lasers, with each cluster only 10 centimeters across.

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