Scientists slowed down light by 10,000 times in experiment: ScienceAlert
Scientists have previously shown that light can be slowed in certain scenarios, and a new study shows a way to do this that promises to be one of the most useful approaches yet.
The researchers behind the breakthrough, from Guangxi University and the Chinese Academy of Sciences in China, say their method could benefit computing and optical communications.
Light moves through the vacuum of space at one speed and one speed only – 299,792 kilometers (about 186,000 miles) per second. However, if you throw a bunch of electromagnetic fields into its path, like those surrounding ordinary matter, that extraordinary speed starts to slow down.
Most transparent materials slow light down a little. It is the changes in speed that cause light to bend as it travels from one medium to another. But putting the brakes on requires special materials like photonic crystals or even ultra-cold quantum gases.
“We envision that our work provides a completely new direction for achieving ultrastrong light-matter interactions in photonic nanochips,” the researchers wrote in their published paper.
The new method relies on what’s known as electromagnetic induced transparency (EIT), which uses a clever bit of laser trickery to manipulate the electrons inside a gas stored in a vacuum, essentially turning it from opaque to transparent.
This means that laser light can pass through it, but because of how it is manipulated, it is also slowed down. This makes it very interesting for physicists, but this approach also means losing a lot of light and energy along the way.
To reduce this loss and improve the efficiency of the entire system, the researchers took some of EIT’s principles in controlling light and designed a new material to slow down light. The material is a type of metasurface – an artificial two-dimensional structure that has properties unparalleled in nature.
The team’s metasurfaces were made of very thin layers of silicon — like today’s computing chips — and turned out to be much better than existing options in the way they retain and release energy (in this case, from light).
Based on the results obtained by the researchers, light can be slowed down by more than 10,000 times in this system. At the same time, light loss is reduced by more than five times compared to other similar methods.
Key to the new approach is the way in which the smallest building blocks of the supersurface – known as meta-atoms – are positioned. In this case, they are close enough to blend together, which in turn affects the way the light is treated as it passes through.
The end result is that all this complex science is to better control how light travels. Since light plays a key role in everything from broadband internet to quantum computing, there are many potential applications.
It’s not the only way scientists have discovered to further slow down light, beyond the natural slowing down that occurs in materials like water, but its effectiveness and scalability make it a promising option for further study.
“With these results, our study opens a new path to tailoring light flux in metasurfaces,” the researchers wrote.
The research was published in Nano messages.