Chinese scientists claim they have discovered how to power stealth submarines with lasers

Chinese scientists from Harbin Engineering University have developed a laser propulsion system that promises a new era of submarine technology. Instead of using a driveshaft and propellers, the proposed system uses advanced laser pulses and fiber optics to generate thrust comparable to that of a commercial jet engine.

The entire system uses only 2 megawatts of laser power, which is within the power limits of a nuclear submarine. This breakthrough in efficiency was previously considered unattainable.

A giant leap forward in submarine propulsion

The technology, formally known as ‘underwater fiber laser-induced plasma detonation wave propulsion’, could theoretically enable submarines to travel at much higher speeds than currently possible. Moreover, there are no turbines or propellers. A laser-based submarine would not produce the mechanical vibrations that are often indicative of a submarine’s location.

The pursuit of underwater laser propulsion is not new. The concept, initially proposed by Japanese scientists twenty years ago, has been difficult to implement in practice due to the inefficiency in directing the propulsive force. However, researchers led by Ge Yang, associate professor at the School of Mechanical and Electrical Engineering at Harbin Engineering University in Heilongjiang Province, claim they have overcome these challenges by introducing mechanisms that focus the laser-generated plasma in a controlled manner and send.

The principle behind this innovation is the creation of bubbles through the evaporation of seawater, a phenomenon known as ‘supercavitation’, which dramatically reduces water resistance. The high-energy lasers fired through an array of optical fibers, each thinner than a human hair, generate plasma in the water, along with a detonation wave.

The innovation lies in exploiting this detonation wave, which extends in all directions and is extremely difficult to control to provide a driving force in a particular direction. The solution involves ejecting small spherical metal particles onto which the detonation force is applied. When the metal particles leave one end of the submarine, the underwater vehicle, along with the laser pulses, is propelled in the opposite direction.

“This method can also be applied to underwater weapons, creating a phenomenon of supercavitation, which significantly increases the underwater range of projectiles, underwater missiles or torpedoes,” Ge said. S.C.M.P.

Challenges and future applications

Previous attempts at this seemingly science-fiction propulsion mode have failed miserably, generating a pitiful amount of thrust. However, experiments conducted by Yang and colleagues suggest that their technology can produce 70,000 newtons of thrust using two megawatts of laser power. That’s the same amount of thrust as a commercial jet engine. However, you need a lot more to move a huge submarine, like the kind used by military personnel.

Despite significant progress, there are still numerous hurdles before this technology can be fully operational in military submarines. These include controlling the heat generated by the lasers, ensuring the durability of optical fibers under extreme conditions. There is also the challenge of integrating the system with existing subsea structures such as anechoic tiles.

Integrating this kind of technology into a supposedly stealthy submarine also raises some intriguing scenarios. Although lasers would indeed remove the noise of mechanical vibrations, cavitation bubbles are certainly not silent. In fact, the opposite may be true. It could make the submarine an obvious target for sonar, casting doubt on the feasibility of such a solution for military applications.

But beyond military use, this technology also holds promise for civilian applications, potentially revolutionizing the way ships are powered and contributing to more environmentally friendly sea travel.

The findings were reported in the Chinese academic journal Acta Optica Sinica.