Ann Arbor Times

The University of Michigan has conducted research indicating that the range of engineered materials suitable for future optical technologies, such as lasers and imaging devices, is broader than previously thought. The study focused on topological insulators, which are materials with unique properties that affect energy and information transmission.

Xin Xie, a research fellow in the U-M Department of Physics and lead author of the study published in Physical Review X, remarked, “We see this as a step toward building a more versatile and powerful foundation for future photonic technologies.”

Topological insulators function primarily as insulators but have conductive outer surfaces. This feature allows researchers to manipulate electricity or light flow for various applications. The U-M team examined topological insulators that confine conduction to their edges while permitting unidirectional flow. Hui Deng, senior author and U-M professor of physics, noted the interest in these systems for transporting photonic information: “They have unidirectional transport and the light can go around defects without scattering.”

Typically, these systems rely on an external magnetic field to exhibit desired properties due to their band gap—a crucial energetic hurdle within the system. A larger band gap enhances edge conduction states' protection, according to Deng.

Previously, research concentrated on one type of band gap design principle from electronics. However, using symmetry analysis and computer simulations, the U-M team explored other methods. They found that coupling certain photonic crystal designs with 2D materials created topological insulators with different band structures.

This discovery broadens the design options for polariton Chern insulators beyond what was assumed possible. Xie commented on the findings: “What surprised me most was how common the required band structures actually are.”

The next phase involves fabricating real-world examples of these simulated systems—a complex task but one aligned with Deng's team's expertise. The researchers estimate these lab-built topological insulators could achieve band gaps up to 100 times larger than current records.

The study received funding from multiple sources including the Army Research Office and National Science Foundation and utilized resources from U-M's Advanced Research Computing Core.