Newly Developed Laser Beam Defies the Laws of Light
The discovery could lead to new communication technologies, which would be useful for military and defense personnel communicating with each other, for instance.
The findings were published in Nature Photonics on June 22.
'Spacetime wave packets'
The term that the team of scientists is calling their new laser beam system is "spacetime wave packets," which have the potential to change the way communication technologies operate.
To explain existing communication methods, these follow what's known as Snell's Law. Put simply, the scientists break down Snell's Law in their study to explain how it works: if you look at a spoon placed in a glass of water, the spoon looks broken at the point where it meets the water. This happens because light travels more slowly through water than it does through air, and the light rays bend when they enter the water.
The new laser beam, however, does not follow this rule of physics, a basic law of light.
"This new class of laser beams has unique properties that are not shared by common laser beams," explained Ayman Abouraddy, principal investigator of the study.
"Spacetime wave packets can be arranged to behave in the usual manner, to not change speed at all, or even to anomalously speed up in denser materials. As such, these pulses of light can arrive at different points in space at the same time."
An example the team uses to explain how their system works is as so: if a plane is trying to send a message to two submarines at the same depth but one is further away from the plane than the other, the closest submarine will receive the message more quickly. However, with its new laser beam, the message arrives at the same time to both submarines so long as they're at the same depth.
The team stresses that their laser beam fits into special relativity, and doesn't fully go against the laws of physics. Their research doesn't change oscillations with light waves, rather, it controls the speeds at which the peaks of the light pulses travel. The team achieved this by using a spatial light modulator.
"Space-time refraction defies our expectations derived from Fermat’s principle and offers new opportunities for molding the flow of light and other wave phenomena," explained Basanta Bhaduri, co-author of the study.