Science Daily June 10, 2024
Recent theoretical studies have suggested that transition metal perovskite oxide membranes can enable surface phonon polaritons in the infrared range with low loss and much stronger subwavelength confinement than bulk crystals. Such modes, however, have not been experimentally observed so far. An international team of researchers (USA – North Carolina State University, Lawrence Berkeley National Laboratory, Stanford University, SLAC National Accelerator Laboratory, Switzerland) studied the phonon polaritons in a 100 nm thick freestanding crystalline membrane of SrTiO3 transferred on metallic and dielectric substrates. They observed a symmetric-antisymmetric mode splitting which gave rise to epsilon-near-zero and Berreman modes as well as highly confined propagating phonon polaritons, both of which resulted from the deep-subwavelength thickness of the membranes. Theoretical modeling based on the analytical finite-dipole model and numerical finite-difference methods fully corroborated their experimental results. According to the researchers their work shows the potential of oxide membranes as a promising platform for infrared photonics and polaritonics… read more. Open Access TECHNICAL ARTICLE
Preparation and structural characterization of SrTiO3 membranes. Credit: Nature Communications volume 15, Article number: 4743 (2024)