The Excalibur program is developing optical phased array technology to enable high-power laser systems that are 10 times lighter and more compact than existing high-power laser systems for use on a broad spectrum of military platforms without degradation of the original platform mission.
In counterinsurgent, counter-terror campaigns, risks
associated with conventional
weapons in combat operations can severely limit their use and
effectiveness, particularly in urban environments. These risks are largely associated with
challenges posed by confining intended effects to adversary combatants and
forces. Even in cases when combat
operations are deemed necessary, the consequences of collateral damage from
conventional weapons can complicate and hinder the overall mission. Laboratory and field testing of high-power
laser systems indicate irradiance levels for functional and lethal effects
against a variety of adversary targets and surgical precision of such lasers
against certain air and ground targets. However, existing high-power chemical laser systems are too
large and too inefficient for deployment on tactical airborne platforms.
The DARPA Excalibur program will develop coherent optical
phased array technologies to enable scalable laser weapons that are 10 times
lighter and more compact than existing high-power chemical laser systems. The optical phased array architecture
provides electro-optical systems with the same mission flexibility and
performance enhancements that microwave phased arrays provide for RF systems
and a multifunction Excalibur array may also perform laser radar, target
designation, laser communications, and airborne-platform self protection tasks.
These phased arrays will coherently combine lower-power
electrically driven lasers, such as diode lasers and fiber laser amplifiers. Coherently combinable single-mode diode
lasers and fiber-based systems can provide overall laser efficiencies greater
than 50 percent and 30 percent, respectively, while maintaining
near-diffraction-limited beam quality.
To produce a weapons-grade system, however, their output power must be
increased without introducing additional optical phase noise and modal
Beam-steering technologies will be pursued to make these
arrays conformal with the airframe, to provide rapid retargeting across a large
field of regard, and to compensate for the effects of atmospheric
turbulence. The Excalibur program will
demonstrate a high-power phased array of kW- class fiber laser amplifiers and investigate the limits of active
optical phase-locking onto uncooperative targets under realistic
Once Excalibur’s technical objectives are achieved, it is
envisioned that a coherent array of 10's of subapertures, each driven with a multi-kW coherently combinable fiber laser
amplifiers, would enable ~100 kW
class laser systems for precision strikes against both ground and air
targets. This technology will enable the
practical use of high-power lasers on a broad spectrum of military platforms
without degradation of their original missions.
Dr. Joseph Manganojoseph.firstname.lastname@example.org