Laser directed energy weapons technology breakthroughs enable them to be deployed on Trucks, Warships and Airplanes

Rajesh Uppal July 18, 2020 Geopolitics, Photonics, Weapons Comments Off on Laser directed energy weapons technology breakthroughs enable them to be deployed on Trucks, Warships and Airplanes 2,246 Views

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 US Navy estimates the “cost per shot” of a laser at less than a dollar: missiles used for ship defense cost $800 thousand up to $15 million dollars each. Compared with conventional anti-missile weapons systems in deployment, the laser DEW would be the most efficient and the most cost-effective, roughly dollar per shot.

Many countries are developing laser based directed energy weapons for battlefield and counter-terrorism operations. Some countries like US, Russia and China have reached high degree of maturity in developing laser based directed energy weapons. “Laser weapons are no longer a technological problem, It’s one of integration at the service level,” according to Lockheed executives. “The technologies now exist,” said Paul Shattuck, company director for Directed Energy Systems. “They can be packaged into a size, weight, power and thermal which can be fit onto relevant tactical platforms, whether it’s a ship, whether it’s a ground vehicle or whether it’s an airborne platform. “That doesn’t mean that giant city-melting lasers are on their way. Right now, the weapons are limited to the 15-30 KW scale; going much further requires figuring out how to deal with atmospheric interference, an issue which becomes more complicated with weapons mounted on airborne systems.”

The Air Force Research Laboratory (AFRL) completed a major milestone under the Self-Protect High Energy Laser Demonstrator (SHiELD) Advanced Technology Demonstration (ATD) Program, in which the surrogate laser weapon system successfully shot down multiple air launched missiles in flight. During the series of tests at the High Energy Laser System Test Facility at White Sands Missile Range, the Demonstrator Laser Weapon System (DLWS), acting as a ground-based test surrogate for the SHiELD system, was able to engage and shoot down several air launched missiles in flight.

The SHiELD program is developing a directed energy laser system on an aircraft pod that will serve to demonstrate self-defense of aircraft against surface-to-air (SAM) and air-to-air (AAM) missiles.The demonstration is an important step of the SHiELD system development, by validating laser effectiveness against the target missiles.

“The successful test is a big step ahead for directed energy systems and protection against adversarial threats,” says Maj. Gen. William Cooley, AFRL commander. “The ability to shoot down missiles with speed of light technology will enable air operation in denied environments. I am proud of the AFRL team advancing our Air Force’s directed energy capability.”

The US Army is moving forward with a new 100-kW laser weapon, awarding US$10 million to Lockheed Martin and Dynetics to continue development of the High Energy Laser Tactical Vehicle Demonstrator (HEL TVD). Designed to counter low cost, high volume threats, the new mobile battlefield laser is the latest in the American effort to produce incrementally more powerful and accurate directed energy weapons. “Laser weapons provide a compliment to traditional kinetic weapons in the battlefield,” Lockheed Martin said. “In the future, they will offer reliable protection against threats such as swarms of drones or large numbers of rockets and mortars.”

Russian Deputy Defense Minister Yuri Borisov has also revealed that the laser weapons are no longer a novelty for the Russian armed forces, with the military already in the process of commissioning and even adopting several types of laser-based weapons systems. China too is involved in the work on laser weapons. In 2014, it was reported that an experiment by the Chinese Academy of Engineering Physics resulted in the downing of a small drone hit from a distance of two kilometers.”

Israeli investments in laser technology have led to the ability to focus laser beams precisely on long-range targets, while overcoming atmospheric disturbances. Encouraged with the new technology breakthrough DDR&D embarked on three parallel high-energy laser weapons demonstrator programs with Elbit Systems and Rafael, designed to demonstrate new laser weapons capabilities.

The UK Ministry of Defence has officially awarded a £30m contract to produce a prototype laser weapon. The aim is to see whether “directed energy” technology could benefit the armed forces, and is to culminate in a demonstration of the system in 2019. The contract was picked up by a consortium of European defence firms comprising the companies MBDA, Qinetiq, Leonardo-Finmeccanica GKN, Arke, BAE Systems and Marshall ADG.

Challenges in Development of Laser Weapons

Laser weapons have to overcome many challenges such as cost, size, thermal management, stability, and power requirements for a laser weapon to become operational. Dirt, dust, wind, clouds, rain, and inclement weather can also hamper a laser’s range.

Subrata Ghoshroy of MIT’s Science, Technology and Global Security Working Group wrote in the Bulletin of Atomic Scientists: Any weapon that relies upon light traveling through the atmosphere runs into the problems of dust, humidity, and fog—features which absorb and scatter the laser energy. In addition, atmospheric distortions such as turbulence can deflect a beam of light. And at the same time that the photons in a laser’s beam must overcome all of these obstacles, they must also stay focused in a tight column and keep advancing forward without diminishing in power. Meanwhile, the user of the laser weapon must account for the movement of the target, the movement of the firing platform, and any decoys, dummies, or multiple war warheads that the enemy throws up.

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. For instance to destroy anti-ship cruise missiles would require a beam of 500 kilowatts and demand megawatts of power.

Chemical lasers are the only systems that have produced megawatt-level outputs, however, they require special handling because of toxic chemicals hence fallen out of favor. Another reason is that they rely on what is essentially an external/independent power source, and thus lack the key strategic value of directed energy weapons: a virtually unlimited magazine.

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.Existing lasers generally dissipate two-thirds to three-quarters of the energy as heat, requiring still-bulky cooling equipment to avoid overheating damage. Air cooling can yield an unacceptable delay between shots.

In turbulent atmospheric conditions, like dust and humidity, the laser must propagate efficiently and stay accurately focused on the target. The system must compensate for the movement of the target, the motion of the platform and the distortion of the beam from weather or environmental conditions.

Laser Weapons require beam control/fire control (BC/FC) system that tracks a target, measures range to the target, compensate for atmospheric turbulence, select an aimpoint (vulnerable area) on the target, focuses and points the laser beam. A high precision target tracking system is needed and beam pointing system having extremely low jitter depending on the distances involved.

Laser beams begin to cause plasma breakdown in the atmosphere at energy densities of around one megajoule per cubic centimetre. This effect, called “blooming,” causes the laser to defocus and disperse energy into the surrounding air. The scintillation of atmosphere also causes severe distortion or beam focusing. This requires Adaptive or deformable mirror consisting of thousands of miniature actuators that continuously predistort the beam for it to remain focused. Coherent and incoherent beam combining technologies are also used to increase the power levels. Battle management systems are also required to manage the weapon.

The high power requirements, large magazines and present low efficiency of lasers imply enormous power supply needed to operationalize laser weapons. Only large cruisers and destroyers have enough power under battle conditions to support lasers as well as additional power generating and cooling equipment.

Professor of Military Sciences Vadim Kozyulin points out, “the problem with laser weapons is that to function they require an enormous amount of energy. The main problem is to create a battery capable of feeding the laser cannon so that it can fire not one but several hundred shots.”

“A series of problems remain unresolved,” Svobodnaya Pressa, said columnist Anton Mardasov. “Firstly, is the problem of excess heat. In the American Boeing-based ‘flying laser’ project, upwards of 80% of pulse energy was lost in the form of heat, and even in testing on the ground the aircraft’s paint literally began to burn away from its intensity.” “Secondly, the issue of the beam being scattered has not been resolved; dust, soot and smoke scatter the laser beam, weakening it. Thirdly, scientists are yet to create an optical lens capable of withstanding powerful laser beams; following one serious pulse, the melted lens needs to be replaced. According to some experts, this, along with the price, is one of the main obstacles to the use of laser-based weapons in space – one shot and the optical lens fails, and the system itself becomes much too hot.”

New technologies breakthroughs enabling development of powerful Laser Weapons

Researchers are working on many enabling technologies of Laser Weapons like high power and efficient lasers, Coherent and incoherent beam combining technologies, high power and energy density sources and counteracting the effects of atmospheric turbulence.

High Power and efficient Fiber Lasers

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.

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.

Both solid state (e.g. slab and rod) and fiber lasers can be diode pumped, and diode power supplies and pump modules themselves are electrically efficient and lend themselves to miniaturization. This efficiency, in turn, reduces the cooling requirements, and all its attendant equipment (pumps, heat exchangers, etc.). Currently, individual fiber lasers can deliver up to about 2 kW of power, but multiple units can be combined to deliver around 10 kW in a single beam with extremely good mode quality.

DARPA Efficient Ultra-Compact Laser Integrated Devices (EUCLID) to develop laser diode pump modules (DPMs)

The laser diode pump modules (DPMs) which power the fiber laser amplifiers are presently a significant driver of system-level SWaP. Low module efficiency increases demand on the power system and the amount of waste heat that the thermal management system must dissipate. Because many modules are needed to power a single fiber amplifier, low packing density of the modules leads to a larger integrating structure and more electrical, cooling, and optical overhead. However, primary development drivers to date have been commercial market priorities, continuous operation for long time periods and long life rather than low size/weight and high efficiency. As a result, there is opportunity for significant size and weight reduction while increasing electrical-to-optical efficiency of DPMs.

DARPA Microsystems Technology Office (MTO) has released the Efficient Ultra-Compact Laser Integrated Devices (EUCLID) BAA, number HR001117S0013. The EUCLID program is soliciting research proposals for the development of highly efficient, ultra-compact, fiber-coupled laser diode modules suitable for pumping high power fiber lasers. The Efficient, Ultra-Compact, Laser-Integrated Diodes (EUCLID) program seeks to drive down the size and weight of diode pump module (DPM) technology while increasing electrical-to-optical efficiency and optimizing modules for dense packaging. To enable significant further near-term reduction in the SWaP of fiber laser arrays, the EUCLID BAA seeks proposals to develop and demonstrate DPMs consistent with SWaP, efficiency, and system compatibility metrics.

Desired DPMs would be capable of being densely packaged with other identical modules in a configuration consistent with integration into line-replaceable high-power fiber amplifier assemblies. DPM output power of ≥ 650 W is desired to minimize packaging and overall system SWaP. The outputs of such modules, when combined, should also allow for efficiently pumping as wide a range of high power fiber amplifier output powers (between 1 kW and 3 KW) as possible. This would provide the flexibility to optimally tailor the array size and output power for various DoD HEL applications.”

Lasertel has been awarded a $1 million,Phase I contract to participate in the Defense Advanced Research Projects Agency’s Efficient Ultra-Compact Laser Integrated Devices program. The project will focus on the development of lightweight laser diode pump sources for fiber lasers used in directed energy applications.

General Atomics’s compact 150 kW High Energy Laser (HEL)

General Atomics revealed in April 2015 that its Gen 3 High Energy Laser (HEL) completed beam quality and power measurements tests. The Gen 3 laser has a number of upgrades that provide improved beam quality, increased electrical to optical efficiency, and reduced size and weight; the assembly is small at only 1.3 by 0.4 by 0.5 metres (4.3 × 1.3 × 1.6 ft), and is powered by a compact Lithium-ion battery to demonstrate deployability on tactical platforms. Beam quality remained constant through the 30-second demonstration, proving that the beam quality of electrically-pumped lasers can be maintained above 50 kilowatts.

General Atomics’s Tactical Laser Weapon Module includes high-power-density lithium-ion batteries, liquid cooling, one or more laser unit cells, and optics to clean up and stabilize the beam before it enters the beam-director telescope. A unit cell produces a 75 kw beam, and modules can be combined to create beams of 150-300 kw in power.

General Atomics is undertaking a privately funded study to integrate a 150-kilowatt solid-state laser onto its Avenger (née Predator-C) drone. GA-ASI has designed a power system for drone lasers that works almost like a hybrid car, the non-plugin kind. “You use the aircraft power to charge an intermediate storage system, and then that runs the laser when it’s doing laser shots,” said Michael Perry, Vice President for Mission Systems at GA-ASI.

Beam combining technologies

However, the power of state-of-the-art single-mode fiber lasers is limited by by thermal and nonlinear effects to 10 KW. Combining multiple low power lasers with good beam quality into one high-power beam helps in overcoming power limitations of fiber lasers. The large number of single mode fiber lasers can be combined either coherently, spectrally or incoherently. Coherent combination is the best technology, but requires extremely narrow laser line widths and precise control of the polarization and phase of the individual lasers.

Israel’s breakthrough in beam control/fire control (BC/FC) system

Israeli investments in laser technology have led to the ability to focus laser beams precisely on long-range targets, while overcoming atmospheric disturbances. The new technology is key for the delivery of laser effects on target within a short time. It will enable the development of laser weapons capable of intercepting a variety of threats.

The new technology will prompt a strategic change in Israel’s defense capabilities.” The IMOD press release said. “Throughout the year 2020, we will conduct a demo of our capabilities.” Israel Head of the Directorate of Research and Development in the DDR&D, Brig. Gen. Yaniv Rotem said We are entering a new age of energy warfare in the air, land, and sea.” According to Rotem, investments in R&D made in the last years have placed the State of Israel among the leading countries in the field of high-energy laser systems.

Encouraged with the new technology breakthrough DDR&D embarked on three parallel high energy laser weapon systems demonstrator programs with Elbit Systems and Rafael, designed to demonstrate new laser weapon capabilities.

A ground-based laser weapon system a field-deployable (containerized) system that will complement the capabilities of the Iron Dome, establishing the lowest tier layer to augment Israel’s four-layered air defense system. This lowest layer will be able to defeat mortar bombs and short-range rockets fired at very short ranges, leaving very short time for intercept. While the Iron Dome missile-based C-RAM has demonstrated the capability to engage those threats, their interception by missiles is too costly to deliver for an optimal response.

The vehicle-mounted laser weapon demonstrator will be tested in C-RAM, C-UAS and APS roles.
A vehicle-mounted laser-based platform protecting maneuver forces, employing a platform-mounted laser system to defend troops in the field against direct and indirect threats (such as rockets, artillery missiles, or anti-tank guided weapons). These lasers will complement the vehicle-specific active protection systems deployed on heavy and future armored combat vehicles, such as the Merkava and Namer, and will provide a higher level of protection for less protected vehicles or troops in the open.

An airborne laser weapon system mounted on an air platform, likely a High Altitude Long Endurance (HALE) or Medium Altitude Long Endurance (MALE) drone, capable of intercepting missile threats above cloud cover, covering wide areas. This concept enables laser interceptors to deploy high above the clouds, thus overcoming the main limitation of ground-based laser weapons. Such a drone-based laser weapon will be able to engage targets before launch or soon after launch, at their boost phase, when the missiles are loaded with propellant and are most vulnerable to damage caused by the laser.

MIT Lincoln Laboratory demonstrates optical phased array

Researchers from MIT Lincoln Laboratory’s Laser Technology and Applications Group were invited by DARPA to Wait, What? to demonstrate the advanced, 101-element optical phased array that they had developed under the agency’s sponsorship. At the Laboratory’s booth, the engineers conducted demonstrations to highlight the capability of this unique fiber laser that coherently combines an array of 101 optical emitters to produce a powerfully bright single beam. A high-brightness, concentrated beam can enhance various applications including directed energy weapons.

The researchers explained to visitors that the challenge in developing this laser is to have the individual beams from all 101 emitters arrive at precisely the same time to a designated point in the far-field plane. To achieve this simultaneous arrival, all the path lengths of the 101 emitters need to be matched to much less than a 1 μm wavelength (less than 1/50th the diameter of a hair). The research team solved the synchronization of the beams by maneuvering a set of phase modulators, which sped up or slowed down the beams such that they all arrived together to create a bright central spot at a target.

The team also demonstrated phase-control algorithm that enabled the phased-array beam to track the moving target. After they showed visitors how to steer a beam and how to compensate for the random fiber path-length variations in an environment that does not have turbulence and atmospheric disturbances, the Lincoln Laboratory team demonstrated beam propagation in a more challenging environment.

They injected hot air into a segment of a beam path so viewers could watch on a monitor how the beam degraded because of the disturbance to it caused by the air’s motion. “Our control algorithm compensated for the disturbance by iteratively applying a correction to all 101 emitters in order to optimize the central intensity of the beam,” said Montoya, who further explained that the algorithm predistorts the 101-element beam before it propagates through an atmospheric disturbance.

Lockheed Martin’s Adaptive Aero-optic Beam Control (ABC) turret

Northrop Grumman has been awarded a USD39.3 million contract related to the development of a laser-based self-defence system for the US Air Force (USAF). Northrop Grumman will develop and deliver an advanced beam control system for integration as part of a complete laser weapons system into a tactical pod for USAF fighter aircraft. Work is expected to be complete by 31 August 2021.

It is intended that the SHiELD pod would better enable the USAF’s fourth-generation fighter fleet, such as the Boeing F-15 Eagle and Lockheed Martin F-16 Fighting Falcon, to survive in contested airspace. The fifth-generation Lockheed Martin F-22 Raptor and F-35 Lightning II would probably not carry the pod, as it would negate their stealth characteristics.

Lockheed Martin in partnership with the Air Force Research Laboratory (AFRL) and the University of Notre Dame, has demonstrated the airworthiness of a new beam control turret to give 360-degree coverage for high-energy laser weapons operating on military aircraft. A research aircraft equipped with the Aero-adaptive Aero-optic Beam Control (ABC) turret conducted eight flights in Michigan.

“These initial flight tests validate the performance of our ABC turret design, which is an enabler for integrating high energy lasers on military aircraft,” said Doug Graham, vice president of advanced programs, Strategic and Missile Defense Systems, Lockheed Martin Space Systems. The ABC turret system is designed to allow high-energy lasers to engage enemy aircraft and missiles above, below and behind the aircraft. Lockheed Martin’s flow control and optical compensation technologies counteract the effects of turbulence caused by the protrusion of a turret from an aircraft’s fuselage.

Deformable mirrors ‘tame’ turbulence for laser weapon

US defense contractor Lockheed Martin says that its optical technology, based around a deformable mirror system similar in principle to that used by large ground-based telescopes to sharpen up astronomical images distorted by the Earth’s atmosphere, can overcome a key technological problem – turbulence. The company has been testing the system, albeit with a low-power green laser on board a business jet, for more than a year.

Counteracting the effects of atmospheric turbulence becomes particularly important when dealing with the long stand-off distances at which airborne laser weapons need to engage with targets – likely to be tens of kilometers, given the speeds involved. Those distances mean that scattering of the laser light by atmospheric turbulence becomes more problematic.

“The aero-adaptive aero-optic beam control (ABC) turret is the first turret ever to demonstrate a 360-degree field of regard for laser weapon systems on an aircraft flying near the speed of sound,” announced Lockheed. “Its performance has been verified in nearly 60 flight tests conducted in 2014 and 2015 using a business jet as a low-cost flying test bed.

”Because enemy aircraft and missiles can come from anywhere, and at very high speeds, an airborne system must be able to track incoming threats with an ultra-rapid response time and then fire in any direction. The company added in a press release: “As the aircraft traveled at jet cruise speeds, a low-power laser beam was fired through the turret’s optical window to measure and verify successful performance in all directions.” The company also announced earlier that it was about to begin production of high-power fiber laser modules for military applications, with the US Army pencilled in to receive a 60 kW system suitable for mounting onto a truck.

Energy generation and storage technologies

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.

One of the advantages of laser DEW is availability of Deep magazines. In contrast to SAM batteries which can carry finite numbers of interceptor missiles in their missile launch tubes, an electrically powered laser can be fired again and again, as long as the ship has fuel to generate electricity (and sufficient cooling capacity to remove waste heat from the laser). Electricity, the total number of shots they can fire is limited only by the amount of chemical fuel available or, in the case of solid-state lasers, the fuel available to drive the electrical power source.

Therefore both of the drivers of increased power requirements to enable wide range of military missions as well as enabling deep magazines increase the challenge of generating operational power requirements as well as thermal management becomes critical.

China develops most powerful super capacitor to power lasers

Now, a research team from Peking University and the Chinese Academy of Sciences led by professor Huang Fuqiang has reported a breakthrough in capacitor technology. In a paper published in the latest issue of the journalScience, they describe how the power density of their supercapacitor can reach 26 kilowatts per kilogram, or 130 times that of lithium-ion batteries.

A supercapacitor (SC) is a high-capacity electrochemical capacitor with capacitance values much higher than other capacitors (but lower voltage limits) that bridge the gap between electrolytic capacitors and rechargeable batteries. They typically store 10 to 100 times more energy per unit volume or mass than electrolytic capacitors, can accept and deliver charge much faster than batteries, and tolerate many more charge and discharge cycles than rechargeable batteries. They are however 10 times larger than conventional batteries for a given charge– some are bigger than shipping containers.

The Yal-1 laser cannon required a power output of one megawatt. A capacitor required to meet that power demand, using conventional technology, would weigh more than 10 tonnes. Huang’s team’s new supercapacitor, in theory, would weigh 40kg. “A significant weight loss in the power unit can reduce the overall mass of a laser system. It can extend the application of laser weapon to fighter jets or even spacecraft,” said Professor Zhu Heyuan, an expert of laser technology at Fudan University in Shanghai, who was not involved in the research. “If the new technology really works and wins a nod from military, a Star Wars weapon may not be very far from us.”

A remaining problem for capacitors is their very low energy-storage capacity, which means their high power output might not last long enough to inflict fatal damage on an enemy target. Huang’s supercapacitor broke the traditional limits of ordinary capacitors with an ability to store 41 watt-hours of electricity per kilogram. Though lower than a lithium battery, it was equivalent to lead-acid cell batteries used in cars today. It was the first time that a capacitor could store as much energy as a mainstream battery.