Militaries developing scalable hundreds of Kilowatts to Megawatts High Power Laser technologies for air and missile defense

The Laser Directed Energy Weapons (DEWs) offer a transformational ‘game changer’ to counter asymmetric and disruptive threats, while facing increasingly sophisticated traditional challenges. Laser technology provides major advantages for military applications over kinetic weapons due to High precision and rapid on-target effect, precise and scalable effects, avoidance of collateral damage caused by fragmenting ammunition, Low logistics overhead and minimum costs per firing.

The key functional components of any laser system are the energy supply and processing blocks that generate power for the pump source that generates an active laser beam by using a laser medium and then feed it to the beam control system. The beam control system consists of beam coupler, beam conditioner, and components that align the beam. Afterwards, the beam is directed towards the target of interest. The impact of laser beam over the desired target(s) is normally evaluated through a sensing and control system. Such a system detects turbulences and inaccuracies induced by atmospheric conditions and relative motion or state transitions of the target(s) and implements appropriate control techniques to apply corrections. These energy lasers have some special requirements for their effective operation, i.e. laser fuel/power requirements, cooling/thermal requirements, tracking and pointing requirements, personal and environmental safety requirements.

The development of laser weapons requires many critical technologies, first is development of lasers capable of generating powers in kilowatts to megawatts range to be able to produce useful damage effects on the target. Laser require a power of the order of 100 kW, to be employed as directed energy weapons, in varieties of missions such as wide-area, ground-based defense against rockets, artillery and mortars; precision strike missions for airborne platforms; and shipboard defense against cruise missiles. To destroy anti-ship cruise missiles would require a beam of 500 kilowatts and demand megawatts of power.

Solid state lasers are electrically powered, and they are separated into three types: Fiber solid-state lasers like LaWS, slab solid-state lasers, and free electron lasers. While they avoid the complicated logistics associated with chemical lasers, SSLs are generally not very efficient. The fiber laser is a variation on the standard solid-state laser, with the medium being a clad fiber rather than a rod, a slab, or a disk and Laser light is emitted by a dopant in the central core of the fiber.

The push to optimize the size, weight and power (called SWaP in military parlance) of field deployed laser weapons has driven a progression in the technology of the gain material used from chemical (e.g. deuterium fluoride), to solid state, and, most recently, to fiber. Fiber lasers have emerged most promising technology, for directed energy weapons due to their many advantages like: high electrical to-optical efficiency (40%), high reliability for operation in harsh military environments, and high beam quality near diffraction-limited light output.

Fiber lasers can satisfy extreme power requirements. The U.S. Navy’s Laser Weapon System (LaWS), tested  by the Naval Sea System Command, has six fiber lasers, each emitting 5.5 kW, incoherently combined into one beam and fired through a beam director . The 33 kW system was used to shoot down an unmanned aerial vehicle (UAV). Although the beam was not single-transverse-mode, the system is of interest because it can be constructed of standard, easily-available components.