The Laser Revolution Part II: Ground, Sea and Grid

The revolution continues! Warfare on the ground and sea will be heavily affected by megawatt-class lasers in the next two decades or so.

And, as we'll see, there are transformative applications in industry, energy generation, transportation and remote sensing.

Beams on the ground

Mobile Tactical High Energy Laser, based on unsuccessful DF reactants

Ground warfare would also be affected by a laser revolution. So far, megawatt-scale lasers have been described as efficient weapons that can reach out into space, burn down massed missile strikes, take out aircraft from extreme range and even catch re-entering ICBM warheads. They’re terrifying too: 532 nm is definitely not eye-safe, and with megawatts involved, mere reflections are enough to destroy retinas from kilometers away. In fact, they’d be starting fires everywhere. A successful beam defence of a city or forest may leave it a burnt-down wasteland if many precautions aren’t taken. But does this mean that they are supreme weapons effective in all domains? Let’s work it out in ground warfare. 

MTU 1975, sporting a 30 kW CO2 laser

A laser weapon as described previously, with a 1 MW output at 532 nm, focused by a 1m diameter mirror, actually fares poorly against armored targets. At the tightest practical spot diameter of 1 cm, it produces an intensity of 12,730 MW/m^2 or 1273 kW/cm^2, and it can maintain this focus out to a range of 10 km. It’s enough to bore through 19 cm/s of steel, 21 cm/s of silicon carbide, 46 cm/s of depleted uranium and 273 cm/s of high density plastic. These are the typical materials of tank armor.

Damaged M1150 Assault Breacher (Based on M1A1 Abrams tank) revealing inner armor layers

The heaviest US tank in service is the M1A2 Abram SEP v2, weighing over 66 tons. Its strongest armor is in the turret cheeks, adding up to around 3.8 + 10.1: 13.9 cm of steel, interspaced with NERA elements made of 80 cm of plastic or rubber sandwiched between thin plates. Together, with sloping, we get a line-of-sight thickness of roughly 18.3 cm of steel plus 105 cm of rubber.

Leopard 2A4 turret armor estimation

The nearly as-heavy Challenger 3 TD has sloped turret cheeks protected by 45 cm of steel and 72 cm of NERA plastic. A T-80BVM has 36 cm of steel with a 12 cm quartz core while Russia’s newest T-14 Armata is thought to have its hull front protected by 65 cm of combined steel and NERA plates. The details of these armor schemes are secret, but as rough estimates this is sufficient. 

A 1 MW laser beam focused onto a 1 cm spot could bore through the strongest armor of the heaviest tanks in about 1.02 - 2.6 seconds. Weaker front armor, like the M1A2 Abram’s 6.7 cm thick steel turret ring or the 8.5 cm thick lower hull plate of the Challenger 3 would only stand up to a 1 MW beam for 0.35 - 0.4 seconds. Thankfully, they are smaller targets that can be easy to hide with proper use of terrain.

T-80 in hull-down position

That incredible performance is however a ‘laboratory conditions’ result where the beam can be accurately held onto a +/- 0.5 cm point, over a target that isn’t moving, bouncing around on its suspension, nor rotating its turret in response to blaring Laser Warning System alarms. In realistic conditions, the smallest movements would move the laser to a new cm-sized spot of armor, restarting the drilling from zero. 

It also ignores the aspect ratio limitations of the hole created by the laser.

A meter deep but 1 cm wide hole has an aspect ratio of 100. A much more realistic result of laser drilling in unprepared outdoor conditions is a 10:1 ratio, meaning that the hole will widen to 10 cm before it reaches a depth of 1 meter. So, the actual amount of material that needs to be vaporized and removed to drill through 1 meter of armor layers is 10^2: 100x, so the actual drilling time is around 102 - 260 seconds.

Combined with the armor moving underneath the beam, we have to conclude that a 1 MW laser weapon cannot reliably defeat the best armor of a tank, and it would take very prolonged firing to deal damage unless it gets very lucky to cross paths with a frontal weak-spot. During that time, the tank will either be moving to cover or firing back. The laser turret itself would have to be stationary to maintain sufficient accuracy, making it even more vulnerable to counter-attack.

At far engagement ranges of 10 km+, the laser will be firing first. The tank may respond by firing its longest range weapon, which in the case of the T-90M’s 125mm cannon is the 3UBK21 Sprinter ATGM with 12 km range.

The older gun-launched ATGM 9М119 Refleks has a shorter 5km max range 

At that distance, the laser has over 30 seconds to find, track and delete incoming ATGMs travelling around Mach 1. It takes several minutes for the tank to be defeated, unless it knows to reverse away from the beam while wiggling its turret and swerving with its hull until it dips behind solid cover. It can assist its retreat with smoke launchers.  

At medium ranges of 2 - 4 km, the tank and the laser turret would probably find and fire on each other at the same time. The laser takes several minutes to reliably destroy a tank from the front, while the tank can fire a high velocity projectile through its main gun. Modern APFSDS rounds are made of tungsten and travel at 1500-1800 m/s, so there is no chance for a laser to do anything about it.

A Challenger 2 managed a tank kill at 10.5 km, supplanting the previous 4.7 km record by a Challenger 1

Worse, the laser turret is a big piece of fragile optical equipment held up high for a better field of view - protecting it the amount of damage needed to destroy it is nearly impossible. At these ranges, a conventional MBT has a strong advantage over lasers.

At shorter ranges, it is a question of luck. Does the laser find the tank in a compromising position, unaware or unable to react, and will it quickly bore a channel through its armor? Or does the tank find the laser first and disable it with whatever ammunition is loaded in its main gun or secondary weapons? 

A laser encountering a tank’s side armor is a very different situation. Modern MBTs are protected by layers worth 5-10 cm of steel, which can be penetrated in a less than half of a second. The hull cannot be rotated as easily as the turret, and drilling a hole with a low aspect ratio is no problem for a laser. A tank caught out of position by such a beam would be defenceless. 

Even so, the damage dealt by a laser is much less than what would happen if a tank is struck by a kinetic weapon or HEAT jet. The result of a laser drilling a hole through armor is… a hole.

X-ray hitcam from 'Gunner HEAT PC' showing the post-penetration damage from an APFSDS round striking an M60A3 turret

There are few ‘post-penetration’ effects to devastate the tank’s interior: no spalling, no hypervelocity fragments nor internal explosions. The beam, once inside, creates an incapacitating shockwave and adds heat that can directly burn occupants in the beam’s path, ignite fuel or set off ammunition reserves, but it has to directly touch these elements to cause damage.

Continuous fire for repeated penetrations is needed to incapacitate a tank, like poking a teddy bear with a needle. In that scenario, it is not particularly better than a large autocannon with armor piercing rounds.

Fearless M2 Bradley IFV engaging a T-90M with a 25mm autocannon

A Bradley IFV could aim a 25 mm Bushmaster loaded with APDS rounds at the side of MBTs and easily penetrate at ranges up to 2 km. A Swedish CV9040 IFV with its 40mm autocannon can penetrate MBT side armor from over 3 km.

 

To summarize, tanks are resistant enough to megawatt lasers that they cannot be used as a main weapon against them. In situations where they are effective, they do not perform better than smaller, cheaper existing weapons.

Big lasers actually make tanks more important on the battlefield.

By serving as efficient air defences out to extreme ranges, they can take out one of the biggest threats to tanks: air power.

Multi-layered air defence combining lasers and missiles.

Today's drone swarms have been reported as the 'death of the tank', while footage of tank columns being destroyed by Hellfire ATGMs and cluster bombs during the Iraq War highlighted how vulnerable tanks could be to air power. Protection from these threats, exaggerated as they may be, can only restore the threat that tanks pose on the battlefield. 

Against lighter vehicles, the 1 MW laser is a menace. MT-LBs, BTR-80s, Strykers or Warriors would melt against such beams. The M3 Bradley has about 40 to 60 mm of aluminium protecting it; this would last about 0.05s under fire. Heavier vehicles like the Puma IFV, T-15 Armata or Namer APC with just as much armor as MBTs would be necessary to survive. The presence of megawatt lasers might still push them much further back behind the front-lines, which in turn makes deploying troops more complicated. But is this any different than their vulnerability to existing threats, ranging from heavy autocannons to MBT main guns? It is more realistic that powerful lasers only have a minor effect on how lighter ground vehicles are deployed.

Lockheed Martin's DEIMOS 50 kW demonstrator.

The consequences for infantry are more drastic. A megawatt beam that can slice through steel would have no trouble with human bodies… although the damage would be less ‘slicing’ than ‘instant steam explosion’. That’s not more or less lethal than other heavy weapons on the battlefield (infantry don’t survive 20mm cannon fire either), and while it can fire continuously without worrying about ammunition reserves, it is more easily stopped by hard cover and deals less damage when it gets through. 

What will change is that large lasers are very good at countering the tools that infantry use to become a threat to vehicles, buildings or aircraft.

Infantry normally poses a threat to tanks, like these Milan ATGM operators

ATGMs can be detected and lased unless fired from very short ranges. Mortar rounds, rockets, RPGs, possibly howitzers would be intercepted too. Drones swarms are eliminated in seconds.

General Atomics 100 kW-class laser that fits inside a standard container

All of these don’t even need 1 MW of beam power to neutralize, as today’s Iron Beam and DE M-SHORAD programs suggest. Without these tools, infantry is limited to fighting other infantry. Against mechanized forces, they must lay minefields or attempt very short-range ambushes, which is a risky tactic even if it does succeed. Hopefully the troops are issued with safety glasses so they are not immediately blinded during the assault.

Finally, there’s artillery. The “king of the battlefield” is likely to lose its throne. A typical 155mm shell is protected by a 1-2 cm thick steel case, which a 1 MW laser can get through in 0.05-0.1 seconds, and it probably takes even less time to ignite the explosive filler inside.

155mm M549 rocket-assisted artillery shell

Radar arrays that quickly detect rounds fired into the air exist already, and they do so at ranges of 30 to 50 km. If a laser turret takes around 1 second to switch to its target and a negligible amount of time to destroy it, then it can defend itself from a combined fire of 60 rounds per minute. That’s six 2S19M2s, ten Caesar 155mms or twelve 2A36 Giatsint-Bs, all firing ineffectively. 

French Caesar 6x6 155mm artillery

However, modern SPGs like the AS-90 or PzH 2000 can also shoot bursts of three rounds in less than 10 seconds. If these rounds are fired from long range and they take 30 seconds to land, then one 1 MW turret can absorb ten bursts. From short range, with 10 seconds of air time, a laser turret may defeat burst fire from three artillery pieces, only for rounds from a fourth piece to go through. Numerous SPGs would then be able to defeat laser defenders within their firing range. Of course, this implies that the artillery pieces have give up their long range capabilities to driver much closer to their target than they'd like.

 

An even simpler approach is to use a multiple rocket launch system. The American M270 MLRS can launch Mach 2.5 supersonic rockets. At their maximum range of 150 km (using ER GMLRS), they would take over 3 minutes to reach their target, taking a trajectory that takes them high into the sky, and therefore a laser turret can intercept 180+ of them. An M270 only has 12 tubes, so it needs to fire from within 12 x 1s x 860 m/s = 10.3 km to overwhelm the laser. The Russian Tornado-G has 40 tubes that fire slightly slower 122mm rockets, able to overwhelm a 1 MW turret from 24 km. If those rockets are loaded with their sub-munition warheads, then they can overwhelm laser defences from even further away, or with fewer launched rockets.

The strongest counter to laser turrets

What’s interesting is that defeating a laser turret using ground forces is much easier than by air strike. A laser could be overwhelmed by a single rocket launcher at short range. An asset worth $20m would be defeated by placing rocket trucks worth $1m at risk. For comparison, an air attack that requires 90 missiles and 12 F-35s in the best case, up to 300 missiles and 38 F-35s in worse conditions, would cost $18-60m if it succeeds and $978-3100m if it fails. Megawatt-scale lasers means advancing on the ground is safer and cheaper than trying to win a war from the skies. So, in the near future, ground wars would need to be won in order for air warfare can be conducted, the opposite of today’s reality of air superiority being a requirement for free ground operations.  

How do ground forces adapt to megawatt lasers?

Main Battle Tanks with their heavy armor would surge in importance. Their armor scheme could be easily updated to protect against laser fire from the sides by the addition of lightweight ablative shields made of graphite. This would greatly improve their durability: a laser intensity that burns through 19 cm/s of steel in ideal conditions only penetrates graphite at a rate of 9.7 cm/s. Graphite is four times less dense than steel, so per kilogram loaded on the tank, it is about eight times more effective than steel.

Indonesian Leopard 2 with AMAP package that drastically thickens side armor

Each armored group on the battlefield would be equipped with a mobile laser turret, to protect against air attack, ATGMs, drones and most threats that prevent them from running rampant. 

This mobile laser turret would probably use an existing MBT chassis to support its multi-ton weight. Power could be derived from existing tank engines, but with additional cooling to handle the resultant waste heat.

Rolls-Royce IPTMS demonstrator using a 300 kW M250 gas turbine to deliver power and cooling for high-power lasers. 

Let’s imagine a 1 MW system sitting on a Leopard 2 chassis. We remove the turret, main gun and ammunition load, taking out around 15 tons. The V12 diesel engine, which provides 1500 horsepower, has an additional link to its gearbox that drives a generator (perhaps weighing 200 kg at 5 kW/kg) to produce electricity. The tank’s cooling system already handles about 1.6 MW of waste heat from the engine, so it needs to be expanded by 63% to also handle waste heat from the laser weapon. 

On top of the chassis will be a tall rotating structure that includes a 2 ton laser generator (2 MW input at 1 kW/kg), a 1.5m ball turret containing a 1m mirror held under armored shutters, a fire control radar, a 100 kWh battery (around 1 ton) and various other equipment that might add another 2 tons, for a total of 6 tons.

The 1K11 Stiletto, showing how a laser turret can use shutters.

Sufficient armor protection to survive machine guns and shrapnel might double this total. In appearance and role, it most resembles the Leopard 2 Marksman SPAAG, but with a 1.5 m wide ball in the center instead of cannons on the turret sides.

It would be just as mobile as a regular Leopard 2, and be able to fire on battery power for a full 3 minutes. This might sound short, but recall that in situations where the laser turret faced missile swarms over the course of several minutes, it spent most of its time switching between targets  and only milliseconds actually destroying them. So 3 minutes of firing would be worth 30+ minutes of operation, depending on how tough the targets are. The onboard generator can then recharge the battery in 6 minutes by running the engine while stopped, or at a slower rate while moving at reduced speed.

1K17 Szhatie Soviet laser tank. It was incredibly expensive due to multiple lasers with ruby lasing rods.

If a stationary 1 MW turret costs $10m, then a 'Laser Leopard' variant is likely twice as expensive at $20m (second-hand Leopard 2A4s to provide the chassis are already under $4m). 

We can also imagine a 'Laser Marder', based on the old Marder IFV platforms or similar lighter platforms, supporting the 'Laser Leopard'.

Marder 1A5A1 IFV

They’d have 250 kW lasers and 0.5m mirrors in ball turrets that replace their current ATGM and 20mm autocannon armament. It might only cost $10m. We calculated previously that at short ranges (under 20 km) the 1 MW laser is overkill for most targets and spends most of its time switching between targets. Additional smaller lasers would maximize the number of targets intercepted. 

Naturally, a counter-laser vehicle could also be introduced.

Directed Energy M-SHORAD vehicles in testing. Their ~0.5m turrets are a good visual reference.

It specializes in destroying laser mirrors. In Part I, we found that a 100 kW laser focused by a 0.5m mirror can destroy the mirror (LIDT 10 kW/cm^2) of a laser turret from a distance of 22 km. A light vehicle can use ground cover and concealment to drive much closer, perhaps to within 10 km. From a hidden position at that distance, it can fire a 20 kW beam focused by a 0.5m mirror to achieve the same destructive effect.

US Army HEL-TVD 100 kW laser by Dynetics.

By 2045 a 20 kW laser weapon system might be small and compact enough to fit on a small off-road vehicle alongside its generator, battery and cooling system, like Raytheon is already attempting with its HEL system on a Polaris MRZR ATV.

It would be sensible to add these systems to future reconnaissance vehicles too, so that they can find targets for air strikes and take out laser defences from their vantage point.

Raytheon's "laser dune buggy'

When large lasers are in play, infantry can do much less than before. They need to be given tools to make them a threat to laser turrets, so they can clear a space for their ATGMs, mortars and other such heavy weapons to become effective again. For example, they could gain small lasers of their own. Today’s infantry is already trained to approach within 5 km of tanks to attack them, and normally have to creep to within 3 km of them to use Stugna-Ps or Javelins. If they can do the same with a 30 cm telescope (it doesn’t need to be a fully rotating turret), then they can produce a spot size of 1 cm and destroy enemy mirrors using only an 8 kW beam. The real question is whether such a laser can be broken down into man-portable pieces that infantry can use within such short distances.

Picture a laser designator, but much larger

Alternatively, infantry can try taking out laser mirrors with a well-timed shot of an anti-materiel rifle when the shutters are open, or get upgraded to very high velocity ATGMs like the defunct MGM-166 LOSAT or the smaller Compact Kinetic Energy Missile which weighed only 45 kg. A future CKEM would shoot a hypersonic dart across 10 km and destroy any target, laser or not.

CKEM fired from fixed tubes on the roof of a Humvee

Artillery can see some modifications too. The number of rounds fired in burst mode becomes their essential performance metric, so an autoloader that can fire ten rounds in ten seconds without melting the barrel might be developed. MLRSs might equip rockets that try to maximize speed over range, so that fewer are needed. But as mentioned before, large 1 MW laser turrets can be backed up by smaller mini-turrets that multiply the number of projectiles they can intercept from short range. If Laser Marders are present alongside Laser Leopards, then the number of artillery rounds or rockets intercepted goes up linearly without also costing much more. Cluster munitions would however increase the number of targets even faster.

Surface Action

HELIOS: 60 kW+ from a Spectral Beam Combined Fiber Laser 

Powerful lasers are already close to deployment at sea. The US Navy’s HELCAP doesn’t need much improvement to jump from 300 kW to 1 MW. We’ve also pointed out the techniques they can use to overcome the beaming challenges at sea, to shoot through atmospheric turbulence, moisture, fog and clouds. In the featureless terrain of the open ocean, lasers are sure to give their best performance. 

The 1 MW green laser focused by a 1 m diameter mirror would already be very effective. It can defend ships from hundreds of subsonic missiles and dozens of supersonic missiles, per turret. It also destroys boats and UAVs out to the horizon, despite only costing as much as a single Phalanx CIWS turret today (assuming it doesn’t get its own independent radar). A ‘bolt-on’ solution (power, cooling, radar included) that can be placed anywhere would be double or triple the cost of the laser alone, but it would be more than worthwhile as a massive air defence upgrade to most of today’s large ships.

Yet, you’ll find the largest ships cost billions of dollars each. It is therefore justified to consider a proportionally larger laser weapon for mounting aboard Navy ships by 2045.

Let’s consider a 5 MW laser focused by a 3 meter diameter mirror. It would cost at least $60 million, or more if it is difficult to construct mirrors of that size. An Arleigh Burke class destroyer has 16 MW of electrical power generation capacity in the Flight III upgrade. Adding a 5 MW laser, which needs 10 MW of electrical input, would require adding a lot more electrical power generating capability and significant battery storage; 1000 kWh to fire continuously for 6 minutes.  

Where the previous 1 MW laser was able to produce a spot intensity of 32 MW/m^2 or 3.2 kW/cm^2 at 200 km, the 5 MW mega-laser extends it to 987 km. It is dangerous to satellites at up to 4000 km altitude, instantly lethal to any aircraft it sees and a great shield against ICBM threats on top of being a large telescope and possibly an effective active sensor in its own right. The line-of-sight limitation however remains.

This is the HMS Daring

If it is mounted on a mast 21 meters high, a position occupied by the Sampson radar aboard the Type 45 destroyer, then it can fire on sea-skimming missiles flying at 10 meter altitude from a distance of 28 km. If the target is a high-flying aircraft, perhaps at 18 km altitude, then the laser can reach it from 500 km away.

A laser won’t be the sole weapon installed. Navy ships are packed with missiles that are not limited by line-of-sight or distance to the visual horizon. Missiles shoot what cannot be seen, while lasers focus on everything that is within line-of-sight. This can include other ships.

Lasers defeating all manner of threats at sea, even at lower power level.

Navy ships are packed with missiles that are not limited by line-of-sight or the horizon. With such a laser on board, a ship can reserve its missiles for anything it cannot directly see, and fire with the laser on anything it can see. This can include other ships. 

Let’s consider ship vs ship combat. As in the air warfare scenario, the side with the laser has a massive advantage, so there would be immense pressure to add these defences to ships as well. Ships can defend themselves from many missiles fired at them, especially if they have both a high-mounted (16m mast) long-range laser and smaller mini-turrets to maximize the number of projectiles intercepted. If we assume a ship has three turrets available (one 5 MW mega-laser and two 1 MW lasers) and target switching time is 1 second, then it can take out missiles as soon as they appear over the horizon. 

The fastest anti-ship attacks are delivered from essentially short-ranged ballistic missiles. China is building up an arsenal of these with missiles like the DF-21, which crosses over 1500 km while climbing to 1200 km altitude before diving down at a terminal velocity of Mach 10. It’s not known if the DF-21’s warhead deploys decoys while outside the atmosphere, or if it carries less re-entry shielding than full ICBM warheads, but even if we assume the worst case scenario, a 5+1+1 MW laser defence system can take out over 120 of them after they hit the atmosphere on their way down. 

Sea-skimming missiles fare better as they spend less time exposed to laser fire. The P-1000 Vulkan is a monstrous 11.7m long missile that can reach Mach 3 while flying only 50 meters over the sea.

It pops up over the horizon from 40 km away, giving defenders less than 39 seconds to respond. In that time, 78 missiles will be destroyed. The Mach 3 Indian BrahMos ramjet missile flies lower: 3 meters above the waves, apparently, meaning it only appears to the lasers from 20.5 km. That reduces the number taken out to 40.

Laser defences with megawatt-scale beams and multiple turrets can take out enormous missile salvos. They can absorb full salvos from 4-5 other ships, even if they’re the largest and most advanced sea-skimming missiles. So, in an equal engagement, no missiles get through. However, from a distance of 25 km, ships would start to become directly visible to each other. 

A warship design optimized for laser weapons

A 5 MW beam focused by a 3m mirror can produce a 1.7cm wide (1.5x diffraction limit) spot at 25 km, enough to cut through 34 cm/s of steel or 151 cm/s of aluminium alloy. If the beam is intentionally widened to 38 cm, then the drill rate is 1 cm/s through aluminium alloy. That is enough to open Domino’s Extra-Large Pizza sized holes in any ship’s hull (5-10mm of aluminium) every second. Ships cannot instantly rotate their hull nor quickly exit the laser fire range, so they are likely to leave any direct engagement with hundreds of such holes.

While there are on-going efforts today to counter directed energy weapons, it is unlikely ships will emerge unscathed from such engagements. Ideas for very long range bombardment using railguns or coilguns could be revived, as hypersonic inert projectiles delivered at a high rate of fire from behind the horizon would be an excellent counter to lasers. The same electrical output installed for laser weapons could be used to power these guns. Eventually, we might see the return of battleship design aspects: multiple large guns, relying on thick (ablative) armor to survive laser strikes and less concerned by air or missile attack... but that's further into the future than 2045.

Pan Spatial's USS Teton futuristic battleship.

Even better than heavy armor is diving underwater… or better still, attack while remaining underwater. Submarines would be largely unaffected by powerful lasers. Even a few meters of seawater is enough to render megawatt beams useless, meaning they’ll remain well protected.

Their main means of attack are torpedoes and missiles launched from underwater. Torpedoes would be as effective as usual. Although heavy torpedoes can travel over 50 km underwater, their practical range against moving targets is greatly reduced (a 55 knot torpedo chasing a 32 knot target only gets 42% its normal range). Submarine-launched missiles like the Exocet SM39 or UGM-84 Harpoon must emerge from the water, forcing them to face laser defences.

MBDA SM40 Exocet with 120 km range

Submarines generally have fewer anti-ship missiles loaded than a surface warship, and can only release a few at once. That means they have only a very limited capability for overwhelming laser defences. However, they are able to launch surprise attacks from unexpected directions, which exploits the greatest vulnerability warships have: being unable to detect they're under attack in the first place.

SLBMs used in an anti-ship role face a similar challenge that regular ballistic missiles do, but they can be deployed in a more flexible and surprising manner than ground-based launchers. The same goes for SLCMs. It still implies that submarines (either large crewed designs or new XLUUV drones) could take on the primary anti-ship role, while regular surface ships focus on anti-air and anti-sub operations.

Anduril's Ghost Shark XLUUV

There are further uses for megawatt lasers, other than sinking ships and felling missiles. Laser light can serve as a power transmitter to any craft equipped with photovoltaic panels. A PV panel specifically tuned to the wavelength of the laser can convert the light it receives into electricity with triple the efficiency of a regular silicon solar panel, up to 86% efficiency. Electrically powered aircraft, like an observation drone, could install laser-PV panels on the undersides of their wings and get recharged by ship beams at sea, allowing them to stay aloft indefinitely. In a further future, those drones could also carry aloft relay mirrors to extend the ship beams far over the horizon. They could be simpler and cheaper mirrors to make them acceptably expendable, all while getting around the direct line-of-sight requirement for laser fire. 

And, while megawatt lasers generally are very harmful to the presence and effectiveness of air forces, they can at least permit them to focus on offensive missions, while laser turrets take on the role of defence. The majority of an Aircraft Carrier Group’s air wing’s time is spent on defensive patrols. Instead, all those E-2 Hawkeyes and F/A-18 buddy tankers could be re-dedicated to serving strike missions. The same can be said for a Navy ship’s missile loadout: it can be mainly offensive instead of nearly entirely defensive, as today.

Instead of an Arleigh Burke-class destroyer dedicating over 60% of its 96 VLS tubes to defensive SM-2s, SM-6s and Evolved Sea Sparrow missiles, they can be filled nearly entirely with LRASMs or the upcoming Naval Strike Missile.    

The only real obstacle to these lasers at sea by 2045 is how long it takes to modify and upgrade ships, let alone design and launch new classes that make full use of new laser weapons! 

Gone with the photon

So far, we have looked exclusively at the military domain. The laser revolution extends far beyond that. 

PowerLight laser power beaming demonstration

What we’d like to see is megawatt-class lasers assisting with transportation, by using them to transmit beamed power. However, this is unlikely to happen in the next 20 years. Shipping and aircraft require too much power while cars and trucks are too numerous to dedicate a beam to each vehicle. 

Ships are large and the most efficient way to move things around.

"ONE Innovation": 24,136 TEU, driven by 62 MW MAN B&W engines to 22 kts

The gigantic Triple E-class container ships are 399m long and 58.6m wide, so their top surface area is roughly 23,381 m^2. If 75% of that area is covered in 20% efficient solar panels, it could generate 3.5 MW of electricity. That’s not enough to match the output of its 2x31 MW diesel engines, and it’s only that much in perfect weather conditions, during the day and without clouds. If those panels are replaced by photovoltaic versions tuned specifically to receive a single laser wavelength, they can reach an efficiency of 68% or better.

A direct free-space optical power link

Even so, they’d need a laser intensity of over 5200 W/m^2 to produce the required 62 MW of power. That’s a pretty dangerous beam to be shooting down at the ocean among commercial shipping lanes: an uncooled surface in the path of that beam would reach a temperature of 550 Kelvin.

Aircraft have it much worse. There are several ongoing attempts at aircraft electrification, from hybrid electric/thermal propulsion to ‘turbo-electric’ architectures to pure electric flight.

NASA next-generation turboelectric aircraft design

While electric motors are approaching the point where they could replace turbine engines at the same power density level (5-15 kW/kg), electric flight is hampered by the insufficient energy density of batteries (40x lower than carbon fuels) and the weight of generators or fuel cells. Lasers can get theoretically rid of these obstacles by delivering power from a remote source. All the aircraft needs to do is install large photovoltaic panels on its underside to catch laser beams, convert them into electricity and use it as needed, without storage.

There is a reason why the MOTH2 UAV is so thin and lightweight

A beamed-power airplane coated in these panels on its underside could feed electrical power directly into electric engines to propel itself, as long as it is within reach of ground-based lasers, allowing it to cross indefinite distances without expending fuel. It is likely to still have an onboard turbine-generator to produce additional power during take-off, or to take over during emergencies. If you don’t want megawatt laser beams wandering over airports near cities, then requiring that electric beam-riding aircraft also have fuel reserves for independent take-off and landings would be fair. 

However, the way aircraft are currently designed does not suit the needs of beamed power very well. If you removed the fuel from a 737-800 until it weighed around 50 tons, for example, and placed it at cruising altitude with a lift-to-drag ratio of 10, then you’d need roughly 50 kN of thrust (which is similar to the 29.4 x 2 kN maximum cruise thrust mentioned here).

Power = Thrust x Velocity, so the plane would need a net engine output of 11 MW at 800 km/h. The plane’s wing and fuselage area add up to roughly 230 m^2, meaning if it was all coated with PV panels, they’d need to pump out 47.8 kW/m^2. Considering 70% efficiency as realistic, that’s an incoming laser intensity of 68 kW/m^2! Far too high. If that beam wandered over a regular airplane, it would produce a temperature over 1046 K, enough to melt its aluminium surfaces.  

Alternatively, go all-in with intense beams to drive a laser-powered turbofan

A flying wing design might double this lift-to-drag ratio in ideal flight conditions, but that would still require dangerous beam intensities.

Instead, lasers could be used to power small drones.

Whether it’s carrying packages or circling above to transmit radio waves or monitor the ground, it is much easier to deliver the electricity they need using beams of modest intensity. Attempts to realize this are ongoing, although there is competition between using lasers to deliver this energy or microwaves.

Laser power transmission exists, but needs to be scaled up 100,000x for humans

Megawatt lasers allow these drones to scale up to the size of light aircraft (the Daher TBM 960 has a 633 kW engine) or medium helicopters (the Leonardo AW09 with 5-8 seats uses a 750 kW turbine), more than capable enough of carrying people. They just need to be equipped with photovoltaic panels of around 20 x 20 meters in size.

Cheap yet powerful lasers could make laser rocket launches practical.

If it takes 1 MW to launch 1 kg to space, and that MW only costs $10,000, then a $100m laser launch facility can start delivering ten ton payloads into orbit.

Depiction of a laser launch facility using many small lasers to minimize costs

A laser launch may last 10 minutes, and the equipment would be around 50% efficient overall, so 1.2 GJ or 333 kWh of electrical energy would need to be expended per launch per kg. That’s $54 at the average electricity prices in the US, but it can be as low as $23 in India! Add in the $10 cost of propellant (mass ratio 2.6 rocket at $6/kg) and other running costs, and you space launch within $100/kg. That’s an order of magnitude lower than the launch costs of chemical rockets (even the Falcon 9 and the upcoming Starship) and promising enough to warrant serious efforts. 

Which suits the next possibility very well.

Megawatt lasers could also open a path to Space Based Solar Power return to being a serious contender for solving the planet’s energy problems.

NASA/Boeing 100 kWe laser-beaming power satellite proposal

Lasers with the right wavelength and assisted with cloud-boring techniques have the advantage of being unperturbed by the atmosphere, and easily focused across very long distances using relatively small focusing mirrors. Chinese plans for this energy source do consider laser beaming, as opposed to typical microwave-based Western designs.

A 2m wide mirror focusing 532 nm beams can produce a spot that’s 24 m in diameter… from geostationary orbit. If 10x solar intensity is acceptable to beam down from space, with an automatic interruption for birds or planes flying through it, then the satellite could deliver 4.5 MW of power all day (3.2 MW of electricity after conversion inefficiency). This should be compared to the kilometer-scale transmitters envisioned for microwave-beaming power satellites that also needed receivers hundreds of meters wide (while also acting as a massive radio jammer for mobile phone or Wifi frequencies), which in turn justified photovoltaic panels growing to the Gigawatt scale.

1970s DOE/NASA solar power satellite studies resulted in gigantic designs

That makes each power station a huge investment requiring billions of dollars each in multiple launches. A MW-scale laser-beaming power satellite could fit inside a single Falcon 9 launch and start operating as soon as it reaches its intended orbit. If that launch is also done using lasers, then it can become cheaper still. 

There are further possibilities with using tightly focused beams to deliver power to spacecraft with electric thrusters across cislunar (10,000 km) distances.

Leik Myrabo designs for power beaming technologies 

A laser-electric drive could rapidly spiral in and out of Low Earth Orbit using small receiver panels (1-5 kW/m^2) instead of titanic solar panels (200 W/m^2) that are 5-25x larger and heavier. Since electric thrusters have many times the specific impulse of chemical rockets, or even upcoming solid-core nuclear thermal rockets, travel between the Earth and the Moon could be done that much more efficiently.

Finally, we can see large lasers being added to the roster of sensors we use to detect and track aircraft and ships, or weather patterns, land erosion and deforestation.

Flying laser sensors are cutting edge technology

They can act as giant LIDARs, which would act as much higher resolution RADAR that with very long range or excellent resolution, that detects radio-transparent objects or illuminate surfaces for other sensors to work on. Such lasers could be mounted on aircraft or observation satellites.

Space based laser detection of submarines

We haven't forgotten laser cutting of metals, but it seems that industry is limited by other factors and therefore more powerful lasers won't help much.

A caution

All that’s been written so far is based on rough calculations, publicly available data and projections decades into the future. Some aspects might not have been covered enough, such as the important role of sensors and electronic warfare in air defence scenarios, or the omnipresent danger of blinding people with large lasers. There will be details that will turn out wrong, either in their optimism or pessimism, but hopefully they’ll be near misses and the general picture remains true (plus or minus a few years). If the sort of future described here starts to take form, then hard questions need to be posed about how nations defend themselves, what role nuclear weapons will have, or whether current spending plans are wise… 

Either way, there will be a laser revolution and like most revolutions, it will shake things up.