Jacinta Bowler
Using lasers to shoot down missiles or drones might be a step closer according to an international team of researchers.
Lasers that destroy or damage objects – like Star Wars blasters – are harder to make work than you might think. Over long distances, the atmosphere spreads the concentrated laser light, which in turn lowers the amount of power arriving an object.
But new research out of the University of South Australia (UniSA), The University of Adelaide (UoA) and Yale University has demonstrated a way to scale up the power of a laser by an order of magnitude, without the beam quality deteriorating over distances.
The answer lies in something long thought unusable for this purpose – multimodal fibre.
“Traditionally people don’t want to use multimode fibre because every mode when it comes out of the fibre doesn’t come out in a well-defined manner – they come out a mess,” Dr Linh Nguyen, a researcher at UniSA, told Cosmos.
“We use multimode fibre to increase the power and then we control the propagating in each mode so that they interfere coherently at the output.”
While most high-power fibre lasers would use a single mode to ensure the beam is correctly firing, using multiple modes acts like a second, third or forth laser all firing at the same time. This increases the power, and using a spatial light modulator, the team can avoid the ‘messy’ multimode issue.
“Our research launches Australia into a world-leading position to develop the next generation of high-power fibre lasers, not only for defence applications, but to aid new scientific discoveries,” said Dr Ori Henderson-Sapir from UoA.
Although Nguyen thinks the technology is still 3-5 years away from being able to be used commercially, he is hopeful it could be used for defence to solve the ‘asymmetric advantage problem’.
“A swarm of cheap drones can quickly drain the missile resource, leaving military assets and vehicles with depleted firing power for more combat-critical missions,” said Nguyen.
“This is known as asymmetric advantage: a cheaper approach can defeat a more expensive, high-tech system by playing the large number.”
He compares this to smashing an expensive car into a cheap one – at the end of the day they’re both scrap.
“Laser weapon research programmes were started in the 60s or 70s, and it’s really had a lot of failures. Governments, particularly the US government, are still throwing money into it, mainly because they know that this could be the only fiscal solution the long run,” he told Cosmos.
“High-power fibre lasers, with their extremely low-cost-per-shot and speed of light action, are the only feasible defence solution.” The research has been published in Nature Communications.