New device, width of human hair, could help investigate physics of light

Physicists have produced a tiny device made of a special material called a photonic topological insulator. The device could help in researching the fundamental properties of matter and light.

Understanding such details, the researchers say, could also lead to the development of more efficient lasers used in medicine and manufacturing.

The study is published in Nature Nanotechnology.

Topological insulators are materials which allow no electrical current to run inside, conducting electricity on the surface of the material. A photonic topological insulator works much the same way, but instead of electricity, it only allows photons – particles of light – to move along its surface.

Making use of this property, physicists can use the material to produce a quantum simulator – a device in which quantum effects can be studied.

“The photonic topological insulator we created is unique,” says Wei Bao, an assistant professor at New York’s Rensselaer Polytechnic Institute (RPI). “It works at room temperature. This is a major advance. Previously, one could only investigate this regime using big, expensive equipment that super cools matter in a vacuum.”

“It is also a promising step forward in the development of lasers that require less energy to operate, as our room-temperature device threshold – the amount of energy needed to make it work – is 7 times lower than previously developed low-temperature devices,” Bao adds.

The device is made from halide perovskite, a crystal composed of caesium, lead and chlorine, and a polymer etched into a pattern on top of the lab-grown crystal.

Crystal and polymer plates were then sandwiched between sheets of various oxide materials. The product is an object only about 2 micrometres thick and 100 micrometres across. This makes it roughly as thick as a red blood cell.

Shining laser onto the device revealed a glowing triangular pattern, a result of the topological nature of the material.

“Being able to study quantum phenomena at room temperature is an exciting prospect,” says Shekhar Garde, dean of the RPI School of Engineering. “Professor Bao’s innovative work shows how materials engineering can help us answer some of science’s biggest questions.”

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