China closing in on laser-propelled fast, stealth subs

China may be moving closer to the holy grail of submarine stealth technology – a propulsion system with no mechanical moving parts. Such technology would eliminate all detectable vibrations, allowing for unprecedented underwater stealth capabilities.

The South China Morning Post (SCMP) reported that Chinese scientists have found a way to significantly improve the efficiency of laser propulsions, which could one day drive submarines.

The report says the new technology can produce nearly 70,000 newtons of thrust, using 2 megawatts of laser power emitted through the submarine’s coating of optical fibers, each thinner than a human hair.

The SCMP report notes that the technology works by leveraging supercavitation generated by laser pulses vaporizing seawater, which can significantly reduce water resistance. It claims that the “underwater fiber laser-induced plasma detonation wave propulsion” eliminates detectable mechanical noise, enabling greater stealth.

To be sure, laser propulsion technology is not new. Twenty years ago, Japanese scientists introduced the concept of using lasers to create plasma in water and harness the detonation wave produced by plasma expansion for propulsion.

However, the idea didn’t progress as the scientists found it challenging to generate a directional driving force as the detonation wave expands in all directions from a single point.

Despite that setback, China and several other countries have funded research on using tiny spherical metal particles to create a force on submarines.

Detonation waves can propel particles in a specific direction, exerting an opposite force on the submarine. Still, the current efficiency is too low to be practical, with 1 watt of laser power generating only