Microscopic Marvel: A Photonic Device that Could Change Physics and Lasers Forever

Rendering of the photonic topological insulator developed in the study. Credit: Rensselaer Polytechnic Institute

Rensselaer Polytechnic Institute researchers have developed the first topological quantum simulator device in the strong light-matter interaction regime that operates at room temperature, revolutionizing quantum studies and laser efficiency, and making advanced research more accessible.

Researchers at Rensselaer Polytechnic Institute have fabricated a device no wider than a human hair that will help physicists investigate the fundamental nature of matter and light. Their findings, published in the journal Nature Nanotechnology, could also support the development of more efficient lasers, which are used in fields ranging from medicine to manufacturing.

The device is made of a special kind of material called a photonic topological insulator. A photonic topological insulator can guide photons, the wave-like particles that make up light, to interfaces specifically designed within the material while also preventing these particles from scattering through the material itself.

Quantum Simulation and Laser Development

Because of this property, topological insulators can make many photons coherently act like one <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="

photon

A photon is a particle of light. It is the basic unit of light and other electromagnetic radiation, and is responsible for the electromagnetic force, one of the four fundamental forces of nature. Photons have no mass, but they do have energy and momentum. They travel at the speed of light in a vacuum, and can have different wavelengths, which correspond to different colors of light. Photons can also have different energies, which correspond to different frequencies of light.

” data-gt-translate-attributes=”[{"attribute":"data-cmtooltip", "format":"html"}]” tabindex=”0″ role=”link”>photon. The devices can also be used as topological “quantum simulators,” miniature laboratories where researchers can study quantum phenomenon, the physical laws that govern matter at very small scales.

“The photonic topological insulator we created is unique. 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. Many research labs do not have access to this kind of equipment, so our device could allow more people to pursue this kind of basic physics research in the lab,” said Wei Bao, assistant professor in the Department of Materials Science and Engineering at RPI and senior author of the Nature Nanotechnology study.

“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 seven times lower than previously developed low-temperature devices,” Bao added.

Fabrication Techniques and Observations

The RPI researchers created their novel device with the same technology used in the semiconductor industry to make microchips, which involves layering different kinds of materials, <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="

atom

An atom is the smallest component of an element. It is made up of protons and neutrons within the nucleus, and electrons circling the nucleus.

” data-gt-translate-attributes=”[{"attribute":"data-cmtooltip", "format":"html"}]” tabindex=”0″ role=”link”>atom by atom, molecule by molecule, to create a desired structure with specific properties.

To create their device, the researchers grew ultrathin plates of halide perovskite, a crystal made of cesium, lead, and chlorine, and etched a polymer on top of it with a pattern. They sandwiched these crystal plates and polymer between sheets of various oxide materials, eventually forming an object about 2 microns thick and 100 microns in length and width (the average human hair is 100 microns wide).

When the researchers shined a laser light on the device, a glowing triangular pattern appeared at the interfaces designed in the material. This pattern, dictated by the device’s design, is the result of topological characteristic of lasers.

Conclusion and Future Prospects

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

Reference: “Topological valley Hall polariton condensation” by Kai Peng, Wei Li, Meng Sun, Jose D. H. Rivero, Chaoyang Ti, Xu Han, Li Ge, Lan Yang, Xiang Zhang and Wei Bao, 24 May 2024, Nature Nanotechnology.
DOI: 10.1038/s41565-024-01674-6

The study was primarily supported by grants from the National Science Foundation and Office of Naval Research.