Fiber lasers have inherent high-efficiency electrical drive efficiency and high-quality beams, and are currently in a stage of rapid development and maturity. At present, the military has not yet made decisions on its development and deployment for high-energy electric laser weapon systems that perform defense and attack missions.
Fiber lasers have advantages that are incomparable to traditional lasers
The US Air Force plans to verify the 30,000-watt fiber laser system developed by Los Angeles (hereinafter referred to as Los Angeles) in 2017, which is an important step. However, the solid-state laser, which competes with fiber lasers, has more than 100,000 watts of power in verification, and is highly mature in technology. It is considered by the military to be a potential targeted energy weapon that can be deployed as soon as possible.
Air Force engineers conduct laser testing
Los Angeles has begun producing fiber laser modules for laser weapons systems with a power of 60,000 watts. In April this year, Los Angeles won a $25 million contract to manufacture and test a modular laser that will be integrated into the Army-owned high-energy laser mobile verification machine (HEL MD). "Our company will deliver lasers to users by the end of 2016," said Rob Afzal, a senior researcher at Lockheed Mart. Previously, Lockheed Mart used internal funds to create a 30,000-watt laser system to verify the feasibility of synthesizing beams with multiple fiber lasers while maintaining beam quality and electric drive efficiency. Afzal introduced that modular technology can integrate lasers at scale and increase the power level by more than 100,000 watts; after the 2017 demonstration, the Army plans to upgrade the HEL MD to 100,000 watts only by adding laser modules.
Los Angeles uses internal funds to create a 30,000-watt laser system "Aladdin"
Compared with solid-state lasers that use flat-panel laser crystals as acquisition medium, laser beams generated by long-term optical fibers formed by secondary pumps have higher quality beams and more efficient electric efficiency, but the power order is lower. The beam of fiber laser is efficiently combined by multiple optical fibers to form a single high-power beam. Los Angeles Company claims that the laser system developed by the company has reached 40%, reducing the power generation and cooling requirements of the entire weapon system. Afzal said that fiber lasers based on beam combinations have greater power and higher beam quality, so they can emit more energy to the target at a longer distance range. In this way, combat distance can be increased or the chance of failure can be reduced, so that the laser weapon system can achieve "fire-observation-fire" to multiple targets. Luoma uses spectral beam synthesis technology. The wavelength of the output of each fiber laser module will be slightly different. The diffraction grids beams by arranging beams one by one to form a single frequency high-power beam, similar to the inverse process of prism decomposing light.
The beam of fiber laser is efficiently combined by multiple fibers to form a single high-power beam
Compared with the consistent beam synthesis technology used by other high-power lasers, spectral beam synthesis technology can obtain the highest "barrel power" efficiency; "barrel power" efficiency is a beam quality measurement method and is a function of the power delivered to the target area. "The problem with in-phase arrays is sidelobes; sidelobe power does not work for the target; in-phase means efficient, but increases complexity. We believe that this type of power and tactical use is not what we are after. We are pursuing the easiest and simplest approach."
Atomic Energy Corporation's third-generation tactical laser weapon module
The 30,000-watt "Aladdin" demonstration system has about 100 fiber laser modules. The Army's 60,000-watt prototype includes a smaller number and higher power level. Afzal explained, "Almost a fiber laser has a power of 1 kilowatt and can also increase energy by 5-10%. This is the biggest advantage of spectral beam synthesis technology." The end of each laser module is a transmission fiber; the fiber is the end of the beam synthesis box. The output after beam synthesis is a single frequency high-power beam that is sent to the laser beam command tower of the weapon system.
Truck-mounted HEL MD, tested its combat energy against mortars and drones against 10,000 watts of industrial fiber lasers
Luoma independently developed fiber lasers due to the demand for high beam quality, but the components used are commercial optical fibers and pump diodes. Two changes have occurred in the laser field: remote communication and industrial cutting/welding. Luoma has made full use of these two reform technologies to develop a new type of laser. Commercial fiber lasers have higher available power, up to 10,000 watts per fiber, but the beam quality is not suitable for beam synthesis. Most ignition tests for laser weapons have so far used commercial lasers, but can achieve power increase by aiming multiple beams at a common point, i.e. partial overlap. This is how the prototype of the US Navy's 30,000-watt laser weapon system was handled. The prototype has been deployed on the amphibious dock transport ship "Ponce" deployed in the Persian Gulf to conduct combat assessments.
The prototype of the US Navy's 30,000-watt laser weapon system has been conducted on the amphibious dock transport ship Ponce
The "Athena" weapon prototype uses the "Aladdin" fiber laser, which failed the engine of a truck during the test. The advantage of modular fiber lasers is that they are variable in scale, easy to cool and package. When using a modular design, you can change the scale and increase the power by adding more modules to the rack. Each module is cooled separately; adding modules will increase the scale of the cooling system accordingly, but the complexity will not increase. The system is parallel, not serial. Before, we often encountered scale adjustment problems. When the power of the laser increases and the plate size is larger, the thermal cooling problem cannot be solved.
Athena weapon prototype using the Aladdin fiber laser failed the engine of a truck during the test
The flexibility of module packaging is another advantage of fiber lasers. The modules can be placed vertically or horizontally, or in two cabinets. All modules are independent of each other and the fiber transmits power. The Air Force Research Laboratory (AFRL) is currently seeking laser weapon systems for the sixth-generation fighter jets; on the sixth-generation fighter jets, the laser module will be installed in a distributed manner throughout the aircraft, and the beams are transmitted by optical fibers that firmly pass through the fuselage, and all optical fibers form a conformal array on the surface of the fuselage.
Air Force Research Laboratory (AFRL) is currently seeking laser weapon systems for sixth-generation fighter jets
Given that laser systems have begun to be manufactured for the Army, Los Angeles is also investigating how to apply fiber laser technology to other needs. Los Angeles is looking for how to package laser systems like the Army's tactical platform, develop a weapon module for warships or install the system into the aircraft's pod.
Boeing’s high-energy laser mobile verification machine (HEL MD) is used in the Army. It chooses to package the laser system
One potential application is the AFRL program’s self-protected high-energy laser verification (“Shield”) project, which is expected to be released soon. The goal of the "Shield" project is to verify a self-defense pod for fighter jets that can anti-missiles by the end of 2020; by the end of 2022, a system with a longer function distance and a power of 100,000 watts will be developed. The Air Force system uses laser technology for self-defense pods, which can scale power to combat offensive weapons mounted by large aircraft, including armed transport aircraft for special operations.
Afzal said, "The technical level of the 'Shield' project is something we can achieve at present, and we will seek to improve it more closely to the Air Force requirements, but not the concept of next-generation systems." However, the key issue is the maturity of fiber laser technology with other solid-state electric lasers. The 60,000-watt laser system tested by the Army has advanced Los Angeles' laser technology to TRL6. Whether it can reach TRL7 depends on how to test whether the system and the system can engage in tactical combat. Competition continues.
