Vacancy-Engineered Phonon Polaritons in a van der Waals Crystal
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| Main Authors: | , , , , , , , |
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| Format: | Preprint |
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2023
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| _version_ | 1866910909377544192 |
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| author | Sakib, Mashnoon A. Hussain, Naveed Stepanova, Mariia Harris, William Bocanegra, Joshua J. Wu, Ruqian Wickramasinghe, H. Kumar Shcherbakov, Maxim R. |
| author_facet | Sakib, Mashnoon A. Hussain, Naveed Stepanova, Mariia Harris, William Bocanegra, Joshua J. Wu, Ruqian Wickramasinghe, H. Kumar Shcherbakov, Maxim R. |
| contents | 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 ($α$-MoO$_3$) via oxygen vacancy formation and lattice strain. Near-field nanoimaging of PhPs in processed $α$-MoO$_3$ reveals an average polariton wavevector modulation of $Δk/k \approx 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 $(1.2\pm 0.2)\%$ compressive strain, resulting in a non-volatile dielectric permittivity modulation of up to $Δ\varepsilon / \varepsilon \approx 0.15$. Despite these lattice modifications, the lifetimes of thermomechanically tuned PhPs remain high at $1.2 \pm 0.31$ 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. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2309_05574 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Vacancy-Engineered Phonon Polaritons in a van der Waals Crystal Sakib, Mashnoon A. Hussain, Naveed Stepanova, Mariia Harris, William Bocanegra, Joshua J. Wu, Ruqian Wickramasinghe, H. Kumar Shcherbakov, Maxim R. Optics Applied Physics Chemical Physics 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 ($α$-MoO$_3$) via oxygen vacancy formation and lattice strain. Near-field nanoimaging of PhPs in processed $α$-MoO$_3$ reveals an average polariton wavevector modulation of $Δk/k \approx 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 $(1.2\pm 0.2)\%$ compressive strain, resulting in a non-volatile dielectric permittivity modulation of up to $Δ\varepsilon / \varepsilon \approx 0.15$. Despite these lattice modifications, the lifetimes of thermomechanically tuned PhPs remain high at $1.2 \pm 0.31$ 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. |
| title | Vacancy-Engineered Phonon Polaritons in a van der Waals Crystal |
| topic | Optics Applied Physics Chemical Physics |
| url | https://arxiv.org/abs/2309.05574 |