Researchers have shown for the first time that a particular type of oxide membranes can confine, or ‘squeeze,’ infrared light. This discovery has the potential to improve next generation infrared imaging technologies. The thin-film membranes are more effective at confining infrared light compared to bulk crystals, which are currently the standard technology for infrared light confinement.Red light is much more effective than bulk crystals for confining infrared light, which is the standard technology. “The thin-film membranes keep the infrared frequency constant but compress the wavelengths, enabling imaging devices to capture higher-resolution images,” explains Yin Liu, co-corresponding author of a paper on the research and an assistant professor of materials science and engineering at North Carolina State University. “We have shown that we can confine infrared light to 10% of its wavelength while keeping its frequency constant, which means that the time it takes for a wavelength to pass is greatly reduced.”The principles of cycling remain the same, but the distance between the peaks of the wave is significantly closer. Techniques involving bulk crystal confine around 97% of the infrared light to its wavelength.
Ruijuan Xu, co-lead author of the paper and an assistant professor of materials science and engineering at NC State, explains, “This behavior had only been a theory before, but we were able to experimentally demonstrate it for the first time through our innovative preparation of thin-film membranes and our novel use of synchrotron near-field spectroscopy.”
In this study, the researchers focused on transition metal perovskite materials. Specifically, Researchers utilized pulsed laser deposition to create a 100-nanometer thick crystalline membrane of strontium titanate (SrTiO3) in a vacuum chamber. The thin film has a high-quality crystalline structure with minimal defects. After growth, the thin films were detached from the original substrate and transferred to the silicon oxide surface of a silicon substrate.
Subsequently, the team utilized the Advanced Light Source at the Lawrence Berkeley National Laboratory to conduct synchrotron near-field spectroscopy on the strontium titanate thin film while exposing it to infrared light. This allowed the researchers to accurately study the behavior of the thin film.researchers have successfully captured the interaction of the material with infrared light at the nanoscale.
In order to comprehend the findings of the researchers, we must delve into the concepts of phonons, photons, and polaritons. Phonons and photons are both vehicles through which energy moves within and between materials. Phonons are essentially the energy waves resulting from the vibration of atoms, while photons are waves of electromagnetic energy. Phonons can be thought of as units of sound energy, while photons are units of light energy. Phonon polaritons are quasi particles that arise when an infrared photon is combined with an “optical” phonon, which refers to a phonon that can
Reflect or absorb light.
“Theoretical papers suggested the idea that transition metal perovskite oxide membranes could confine infrared light through phonon polaritons,” Liu explains. “Our research now demonstrates that the phonon polaritons are able to confine the photons and prevent them from spreading beyond the material’s surface.
“This study establishes a new category of optical materials for controlling infrared light, which could have potential applications in photonics, sensors, and thermal management,” Liu adds. “Just imagine the possibility of designing computer chips that could utilize these materials.The team of researchers found a way to produce thin films that can release heat as infrared light. This method is significant because it allows the thin films to be easily integrated with various surfaces, making it possible to use them in a wide range of devices. The study was supported by the U.S. Department of Energy and the National Science Foundation.
