They’ve utilized a mix of gold and lithium titanate to create a new meta-material that can trap light in orbit around itself much in the same way electricity travels through a circuit.
A metamaterial characterized by it’s microscopic boomerang shaped golden antennas on top of a crystal lithium titanate foundation. For this particular experiment they fired a pulse of red light near the material, and discovered that the resulting photons would begin orbiting around it. The running theory being that properly shaped golden particles can create a path for electromagnetism (light) to travel along.
“We manage to get the light bullet to go around in a circular path,” says Roberto Merlin, a professor of physics at the University of Michigan who led the work, in a recent issue of Science.
It was indeed a circular path but the red pulse itself only completed half a circle along that path, so more work needs to be done before any potential applications arise. The new metamaterial is strikingly similiar to how you’d expect a large scale room temperature time crystal, or skyrmion to behave, both of which possess similar electromagnetic circuitry on a separate scale. However the former two ‘alternate states of matter’ require extreme vacuum conditions and/or temperatures nearing absolute zero.
To travel in a circle, a beam of light must accelerate, in this case surpassing the normal speed of light in the material.
(Nothing can go faster than the speed of light in a vacuum, but light moves more slowly when it’s passing through matter.)
That acceleration generates an electromagnetic field in the crystal, which emits the extra energy as radiation at around 1 terahertz.
So-called T-rays exist in the far infrared part of the electromagnetic spectrum, just below microwaves.
useful in airport security, for example, because they can spectrographically identify substances, and they penetrate many materials without causing harm because, unlike X-rays, they’re not ionizing radiation
The researchers only managed to get the red light pulse to travel in a half a circle, and only 5 percent of the red light was converted into T-rays.
The terahertz emission was broadband, which is useful for spectroscopy, but a narrower frequency would be preferable for other applications.
“It would be fantastic if we could get the light to go around many, many, many times,” Merlin says.