Discovering new methods to decelerate fleeting light waves or even halt them entirely could pave the way for the creation of more sophisticated photonic equipment, such as lasers, LED screens, fiber optics, and sensors.
Using a cleverly designed trap created from a silicon crystal modified to simulate deformation, scientists have unveiled a novel method to make light waves completely stationary.
There are a few techniques to stop light, including cooling atom clouds or intertwining light waves. This innovative method, developed by researchers at AMOLF and Delft University of Technology in the Netherlands, offers benefits that could translate into new technological advancements.
“This technique presents a fresh strategy to slow down light fields, thereby boosting their intensity,” explains physicist Ewold Verhagen from AMOLF. “Implementing this on a microchip is especially crucial for various applications.”
The research team focused on electron manipulation within two-dimensional materials like graphene. In conductive materials, electrons travel freely, speeding along as if on a miniature freeway. However, applying a magnetic field can confine these electrons to specific energy states known as Landau levels.
It’s not just magnets that can force electrons into Landau levels. Single-layer graphene can achieve the same effect. Normally, graphene conducts electricity; but by altering its structure, like stretching it, electrons can be confined to Landau levels, turning a conductive substance into an insulator.
Together with René Barczyk from AMOLF and Kobus Kuipers from Delft University, Verhagen explored whether a material could affect photons in the same way that distorted graphene affects electrons.
They discovered that light could be manipulated with a material similar to graphene, called a photonic crystal, and found they could halt light waves similarly.
“A photonic crystal usually has a regular, two-dimensional pattern of holes in a silicon layer. Light moves freely within this material, much like electrons in graphene,” Barczyk notes.
“Distorting this pattern in just the right way deforms the structure and thus traps the photons. This is our method for creating photon Landau levels.”
The team’s photonic crystals, designed with a honeycomb structure, could trap light in Landau levels through various deformations like bending or twisting. They were also capable of inducing different deformations in different parts of the same material, allowing light to move freely in some areas while being confined in others.
Although further development is needed, this discovery moves scientists closer to precise light control on microscopic scales.
“This advancement brings applications on chips closer,” Verhagen states.
“If we can confine light on the nanoscale and halt it like this, its power will be significantly magnified, not just in one area, but across the entire crystal surface. Such concentration of light is crucial in nanophotonic devices, for instance, in the development of effective lasers or quantum light sources.”
This research has been published in Nature Photonics.
