2023/09/11 by Mashnoon Alam Sakib, Naveed Hussain, Sakib, Mashnoon A. +11 · 1 citation
Engineering · Physics and Astronomy · #Applied Physics (physics.app-ph) #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Mechanical and Optical Resonators #Optics (physics.optics) #Photonic and Optical Devices #Thermal Radiation and Cooling Technologies
paper · pdf · doi:10.48550/arxiv.2309.05574
openalex publication_date 2023/09/11 · openalex created_date 2023/09/13 · openalex updated_date 2026/07/28
Phonon-polaritons (PhPs) in low-symmetry van der Waals materials confine mid-infrared electromagnetic radiation well below the diffraction limit for nanoscale optics, sensing, and energy control. However, controlling the PhP dispersion at the nanoscale through intrinsic material properties-without external fields, lithography, or intercalants-remains elusive. Here, we demonstrate vacancy-engineered tuning of PhPs in α-phase molybdenum trioxide (α-MoO3) via oxygen vacancy formation and lattice strain. Near-field nanoimaging of PhPs in processed α-MoO3 reveals an average polariton wavevector modulation of Δk/k ≈ 0.13 within the lower Restrahlen band. Stoichiometric analysis, density functional theory, and finite-difference time-domain simulations show agreement with the experimental results and suggest an induced vacancy concentration of 1% - 2% along with (1.2± 0.2)% compressive strain, resulting in a non-volatile dielectric permittivity modulation of up to Δε / ε ≈ 0.15. Despite these lattice modifications, the lifetimes of thermomechanically tuned PhPs remain high at 1.2 ± 0.31 ps. These results establish thermomechanical vacancy engineering as a general strategy to reprogram polaritonic response in vdW crystals, offering a new degree of freedom for embedded, non-volatile nanophotonics.