Through microfabrication, a laser beam shot in a glass circuit was made to interact with itself. Scientists managed to create self-sustaining wave patterns called solitons. If you'd like a simple visualization of the phenomenon, this YouTuber has one. Microfabricated glass is a kind of photonic topological insulator.
The research on topological materials previously earned a Nobel Prize to Michael Kosterlitz in 2016. These kinds of materials carry the property to preserve the wave flow passing through them, preventing disorder and defect.
The field of electronics is perhaps more widely-known among people, but there's also the field of photonics, notes Mikael Rechtsman, Physics department professor at Penn University. He lists some of the applications of the field in solar energy, laser cutting manufacturing, fiber optics, and lidar (which is recently adopted in autonomous vehicle technology and archeology). Topological materials show the potential to make photonic devices more efficient energy-wise and more compact.
In the experiment, researchers flashed a laser through a modified glass with precise tunnels carved through it called "waveguides". They resemble a grid formation, but the waveguides are not straight lines, they make regular twists and turns looking like a traveling snake.
With laser beams forcing through it, through the Kerr effect, the properties of the glass are altered. Through this, the researchers got protons to interact, which typically do not interact. As they increased the energy, they saw that the light did not diffract (meaning scatter). Instead, it began traversing in spiral-like patterns. This spiral traversal confirms the device being topological.
As Mikael Rechtsman puts it “Under normal circumstances, photons are oblivious to one another, You can cross two laser beams and neither will be changed by the other. In our system, we were able to get photons to interact and form solitons". The reason for this is the intensity of the laser, altering the properties of glass, through this, photons become "aware" of each other as their environment is changed.
This research has been an important step in developing practical applications for topological systems, especially those requiring high optical power added Rechthsman.