A team of researchers at North Carolina State University (NC State) has made significant strides in the field of infrared light manipulation. Konnor Koons, along with his colleagues, published a paper titled “Low‐Loss Far‐Infrared Surface Phonon Polaritons in Suspended SrTiO3 Nanomembranes” in the journal Advanced Functional Materials. This study demonstrates that thin films can enhance the propagation of infrared light. This improvement bodes well for future applications of AI and other technology.
The research uncovers three distinct benefits to these ultra-thin films. They demonstrate the unique capability to trap both far-infrared and midinfrared light while achieving low energy loss in propagation. This is especially important because it enables light to travel longer distances at greater energy efficiencies.
Konnor Koons, a Civil Engineering Ph.D. student, was first author on the paper. To pursue this idea, he collaborated with co-corresponding author Yin Liu and assistant professor Ruijuan Xu, both of NC State’s materials science and engineering department. The authors investigated long-range low-loss far-field surface phonon polaritons (SPhPs) in suspended strontium titanate (SrTiO3) membranes.
So far, their preliminary results suggest that strontium titanate has the lowest loss characteristics of all. This allows light passing through these films to lose very little energy to heat, increasing its efficiency. Ruijuan Xu elaborated on the significance of knowing these films’ inherent characteristics, saying that
“To better understand the film’s intrinsic characteristics, we suspended the thin film so that it was not in contact with a substrate and conducted a series of tests at the Advanced Light Source at Lawrence Berkeley National Laboratory. And there were two exciting results.”
To increase the thin films’ potential applications, the researchers verified that their films can successfully confine far-infrared light. In the past, tests done on silicon substrates only permitted for the confinement of mid-infrared light. Xu noted,
“When we tested the strontium titanate on a silicon substrate, it could only squeeze mid-infrared light.”
This breakthrough demonstrates that the thin films can be integrated onto various substrate materials and shapes without compromising their low-loss properties. Liu remarked on the scalability of their technique for creating these thin films:
“Another exciting aspect of these materials is that the technique we use to create these thin films is more scalable than the techniques used to create other polaritonic materials.”
The implications of this research are vast. Liu highlighted that the ability to operate across a broader range of infrared wavelengths could significantly enhance thermal management technologies and molecular sensing technologies:
“For example, it will be useful in engineering thermal management technologies to convert heat into infrared light. And being able to operate in a broader range of infrared wavelengths also expands the utility of these materials for developing molecular sensing technologies.”