In a new study, a team of researchers has shown a new approach to 'squeeze' or confine infrared light.
Travelling Particles
Energy can travel between materials through phonons and photons. Phonons refer to waves of energy caused by the vibration of atoms, whereas photons are waves are essentially waves of electromagnetic energy.
Phonons can be compared to units of sound energy, while photons represent units of light energy. Phonons polaritons are quasi particles which are produced when an infrared photon is coupled with an "optical" phonon. This means that they are actually phonons that can either absorb or emit light.
In terms of imaging technologies, scientists currently use bulk crystals as the current established method to confine infrared light.
Squeezing Infrared Light With Oxide Membranes
In the paper "Highly confined epsilon-near-zero and surface phonon polaritons in SrTiO3 membranes," researchers from North Carolina State University worked with transition metal perovskite materials. Led by materials science and engineering assistant professor Yin Liu, the team used the technology at the Advanced Light Source of the Lawrence Berkeley National Laboratory.
Liu and his team used pulsed laser deposition in frowing a 100-nanometer thick crystalline membrane of SrTiO3 in a vacuum chamber. The crystalline structure of the resulting material is high quality, which means that only a very few detects can be seen. Then, the researchers removed the thin films from the substrate and were placed on the silicon oxide surface of a silicon substrate.
The authors were able to prove that it is possible to confine or squeeze infrared light to 10% of its wavelength while maintaining its frequency. This means that the amount of time it takes for a cycle of wavelenght remains the same, while the distance between the peaks of the wave gets closer. Meanwhile, the technique that uses bulk crystals can confine infrared lght to around 97% of its wavelength.
Such behavior was only theorized before, but the research team successfully demonstrated it experimentally by using thin-film membranes and synchrotron near-field spectroscopy. These methods enabled the researchers to detect the infrared interaction of the material at the nanoscale level.
The result of the study reveals that the thin-film membranes are capable of maintaining the desired infrared frequency. Aside from this, they also compress the wavelengths, enabling imaging devices to capture images with greater resolution.
It was found that the thin-film membrane are better than bulk crystals in squeezing infrared light. This can pave way for next geenration imaging technologies using infrared light.
Liu and colleagues have proven that their work establishes a new class of optical materials which can control light in infrared wavelengths. It also has potential applications in various fields, particularly sensors, photonics, and thermal management. In the future, computer chips can be designed with these materials used to shed heat by converting this energy into infraed light.
The researchers believe that their finding is an exciting one because the technique they used in creating such materials confirms the ability of thin films in integrating with a wide variety of substrates. This makes the material easy to utilize in various types of devices.
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