Zapping enemy targets: Viable laser weapons remain critical to military strategy

From the lightsabers of Star Wars to the planet-destroying beams of the Foundation series, lasers convey a disarming glamorization of power and death, delivering justice, revenge, defeat, or redemption at the push of a button. They suggest that a civilization that can tame such power into so narrow and glorious a beam should surely be equal to any, in any galaxy.

In reality, lasers as weapons are rarely used in combat, and the development of laser weaponry has been a more methodical and challenging process, balancing a fine line between aspirations and practical constraints.

To make a laser that could cut through an enemy missile, we would need so much power that the operating machinery would fill a whole room. In addition, a real-life battlefield is a tableau of chaos, smoke, dust, dirt, and deception—all of which can interfere with a laser beam as it seeks and follows a moving target. All of these place demands on battlefield lasers.

Yet, none of these demands appears to be insurmountable, and can be reached with incremental advances of current technology. While disruptive innovation is always welcome, we don’t necessarily need a disruption to get to viable laser weaponry.

Lasers have significant advantages over conventional weaponry that make them a highly desirable military technology. While most military weapons eventually run out of ammunition, lasers can keep firing as long as there is power. Importantly, lasers work at or near the speed of light and hence there is no known technology that can anticipate the arrival of a laser beam.

Another strategic implication of laser weapons is their potential role in electronic warfare. By targeting and disabling enemy sensors and communication systems, lasers could disrupt the command-and-control capabilities of adversaries, providing a significant tactical advantage.

Lockheed Martin's 50kW-class DEIMOS (Directed Energy Interceptor for Maneuver Short-Range Air Defense System) is a ruggedized tactical laser weapon system that can be integrated into the Stryker combat vehicle. Photo credit: Lockheed Martin

Consequently, laser or directed-energy weapons (DEW) continue to be critical for modern military strategy and, according to a 2023 report by the US Government Accountability Office (GAO), the US Department of Defense (DOD) spends $1 billion annually on them. Directed energy weapons operate on the concept of using focused electromagnetic energy to disrupt, degrade, or destroy military targets. At their core, laser weapons emit highly concentrated beams of light, primarily in the infrared spectrum, capable of delivering intense heat and light to a target almost instantaneously.

Laser weapons are different from other types of DEW which use high-power microwave radiation. While both of them can be used to disarm unmanned drones and electronic equipment, lasers use a tight beam while microwaves—because of their much-higher wavelength—are spread out.  GAO reports that laser beams can cut through steel and aluminum in a matter of seconds making them far more lethal in a battle than microwaves.

In 2023, Lockheed Martin delivered a 300-kW laser, dubbed “Valkyrie,” to the DOD. It is a prototype developed under the US Army’s Indirect Fire Capability-High Energy Laser program. As a prototype, Valkyrie, according to a press release from the company, will not be deployed in battle and is meant to “complement other layered defense components to protect soldiers from threats like unmanned aerial systems, rockets, artillery, and mortars, along with rotary and fixed-wing aircraft.”

However, Valkyrie is a giant leap over existing laser weapon systems capabilities, the best of which have laser power of only 50 to 60 kW.

The US Army’s “Guardian” short-range air-defense laser weapons system reaches only 50 kW of power from its mount on the Stryker eight-wheeled armored vehicle. Guardian was developed by Raytheon, which claims that’s enough laser power to counter some incoming drones and winged aircraft. However, Guardian is still under development, and we don’t know completely how effective it would be in real battle.

The US Navy’s HELIOS, or High Energy Laser with Integrated Optical-Dazzler and Surveillance system—mounted on several Arleigh Burke-class missile destroyers—generates 60 kW of power, which can destroy small watercraft, but is not effective against weapons such as missiles.

Compared with Guardian and HELIOS, Valkyrie’s 300-kW laser showcases not just a leap in the power and efficiency achievable for laser weapons systems, but also highlights a significant reduction in size and weight, making laser weapons more practical on the battlefield. Such advancements represent critical milestones in making the once-fictional laser technology a tangible asset in modern warfare.

Power is the main but not the only requirement for a battlefield laser.

A typical laser pointer that we use for PowerPoint presentations consumes about 5 mW of power. A laser that can cut through steel requires 1 kW or about 200,000 times as much power.

The 300-kW laser is therefore a significant jump in “lethality,” which is a measure of how effective the laser is in a real battle. The GAO report notes that Valkyrie’s laser can potentially cut through the nose cone of missiles that cannot be destroyed by most other weapons systems.

To get to this amount of power is not easy. For one, as laser power climbs higher, the machinery required to produce a high-energy beam gets bulkier and heavier. The HELIOS laser, for example, weighs more than 8.5 tons, according to a 2019 report in Breaking Defense. That’s more than the artillery, including guns, ammunition, and mounting, that the laser weapon is meant to replace. Further, the laser is mounted on a 77-ton light aircraft, which means that it is almost 10 percent of the mass of its carrier vehicle, according to specifications provided by the US Air Force.

The US Special Operations Command (SOCOM) is also exploring the use of laser weapons on airborne platforms. A key project involves installing a 60-kW laser weapon on AC-130 gunships. The task poses unique challenges due to limited space on the aircraft. The lasers are intended to complement or replace existing armaments, such as the 30-mm cannon.

The bulkiness of laser weapons comes from the laser-light source. As the laser gets more powerful, the machinery required to produce and maintain the beam gets correspondingly larger, adding to the challenges in integrating high-power lasers into battlefield artillery. A possible solution is to use multiple light sources of lower power, whose output is then combined at the emitter through fiber optic cables.

The light source is usually a solid-state laser. High power means that these sources run the risk of overheating, which necessitates that they be used in pulses to allow time for cooling between shots and that they also have a cooling system that continuously cycles heat away from the source. Many modern laser weapon systems produce the weapon beam by combining the light output of several smaller lasers.

One possible solution to the problem of bulkiness and weight on the battlefield is to use a tether to connect the source and the beam—a little like a corded telephone. A review article by researchers at the US Naval Research Laboratory showed that by combining four fiber lasers with a combined power output of 5 kW, light could be propagated to a target 3.2 km away in a turbulent atmosphere. The light of each laser is transferred via a fiber-optic cable to an output, which could be physically separated from the source. For example, the laser beam could be produced inside the ship and transported to a laser gun located on the stern.

Another problem for laser weapons systems is interference from environmental conditions. If there is dust or particulate matter on the lens of a laser gun—as is easily bound to happen in the battlefield—the laser beam will heat this matter, which can damage the light source itself.

Further, high turbulence in the path of the laser makes it difficult for the beam to be located precisely on the target, which in turn is often moving at high speeds. In addition, atmospheric moisture and dust absorb laser light, reducing the effectiveness of laser weapons. For that reason, airborne lasers on high-altitude aircraft fare better than those used by ground troops, since atmospheric turbulence is greater at lower altitudes, according to GAO. Another mitigation option actively being investigated is for the laser weapon to use wavelengths of light that are not absorbed by moisture or dust, such as those in the visible and mid-infrared.

The US Army's Indirect Fire Protection Capability-High Energy Laser (IFPIC-HEL) prototype program is a 300-kW class laser system. Photo credit: Lockheed Martin

Once again, the higher the power of the laser, the greater the effect of turbulence. Craig Robin, a senior scientist at Army Space & Missile Defense Command told Breaking Defense that if a 1-kW laser suffers x interference in certain conditions, a 100-kW laser will suffer exactly  100 times that interference. So, we can easily understand the problems faced by a low-powered laser and extrapolate this to gauge the effect on military grade equipment.

Laser weapons are increasingly harnessing the power of adaptive optics to overcome the challenges posed by a turbulent atmosphere. Much like a telescope tracking a distant star, laser weapons employ adaptive optics by emitting a laser beam with a precisely known wavelength, targeting an object under challenging atmospheric conditions. As the laser beam travels through the turbulent atmosphere, it encounters distortions and fluctuations. It turns out that these distortions affect both the laser beam and the intended target in a similar manner.

By continuously monitoring and analyzing how the laser beam is altered by atmospheric turbulence, laser weapon systems can deduce the distortions that the target, whether it’s a moving vehicle or an aerial threat, also experiences. This real-time information is then utilized to dynamically adjust the system’s optics, often deformable mirrors, to counteract these atmospheric effects.

In practical terms, this means that laser weapons equipped with adaptive optics can maintain a precise and focused beam on their targets, even in the presence of atmospheric turbulence. According to Donald Puent at the US Naval Academy, this technology significantly enhances the accuracy and effectiveness of laser weapons, making them more formidable in scenarios where precision and target tracking are critical, such as anti-missile defense systems or counter-drone operations.

 After power source and turbulence, a third challenge in developing battle-worthy laser weapons are the logistics of operating a high-performance device under the constraints of realistic battle environments.

As might be expected, the laser source needs a large and abundant supply of electricity, which is not easy to procure in all environments. The power source also needs to be mobile, as defense systems are always on the move.

The integration of laser systems into existing military platforms is another significant challenge. Each platform, whether it’s a ground vehicle, a naval ship, or an aircraft, presents unique constraints in terms of space, weight, and power availability. Designing laser systems that can be adapted to these varied platforms without compromising their operational capabilities is a complex engineering and logistical feat.

Laser weaponry development is thus a blend of engineering innovation and strategic foresight. As these technologies mature, they are set to offer unprecedented capabilities on the battlefield, potentially changing the face of modern warfare.

In the realm of missile defense, for example, lasers offer a promising solution for intercepting and neutralizing both ballistic and cruise missiles. Their ability to deliver precise, high-energy strikes at the speed of light makes them an attractive option for countering fast-moving aerial threats. During ground warfare, laser weapons could be used for point defense against rockets, artillery, and mortars. Their precision and rapid response capabilities make them ideal for protecting critical assets and installations from such threats. The Army’s Guardian truck-mounted laser system is a step towards realizing this application.

However, it’s important to temper expectations with the current state of technology. While laser weapons offer numerous strategic advantages, they are not yet a panacea for all military challenges. Their effectiveness can vary depending on environmental conditions, and certain technological limitations still need to be addressed.

At the same time, no other weapon synthesizes modernity and defense as effectively as a laser. In the future, as we defend from terrestrial, and possibly even alien forces, laser weapons could be the quintessential weapon, winning wars and defeating enemies at the speed of light. 

Vineeth Venugopal is a science writer and materials researcher who loves all things and their stories.