{
  "abstract": "128$^\\circ$Y-cut lithium niobate (LN) laterally field-excited higher-order antisymmetric bulk acoustic resonators (XBARs) have attracted interest for high-frequency acoustic devices thanks to their high electromechanical coupling coefficient ($k^2$), high quality factor ($Q$) from low metal coverage ratio, and thickness-defined resonant frequency. So far, the in-plane orientation of these resonators is commonly chosen to maximize $k^2$, thereby maximizing bandwidth. More recently, in-plane-rotated XBARs in 128$^\\circ$Y-cut LN have been built to provide greater design flexibility in filter synthesis. However, the in-plane anisotropy of $Q$ has been far less explored. This leaves an important gap in understanding whether the propagation direction that determines $k^2$ also affects $Q$. In this work, we investigate the anisotropic $Q$ of higher-order antisymmetric modes (namely, A$_3$, A$_5$, and A$_7$) in 500-nm-thick 128$^\\circ$Y-cut LN on Si. By characterizing resonator performance in various in-plane orientations, we observe that both Bode $Q$ and $Q_{\\mathrm{3dB}, f_p}$ show minimum values at 90$^\\circ$ to the material x-axis and maximum values around 0$^\\circ$, following a trend similar to $k^2$. The A$_3$, A$_5$, and A$_7$ modes around 10.4, 17, and 24 GHz exhibit averaged Bode $Q$/$Q_{\\mathrm{3dB}, f_p}$ values of 735/556, 204/149, and 59/37, respectively. At 90$^\\circ$, the average Bode $Q$ values are reduced to 66, 9, and 12. Finite element analysis (FEA) results suggest that the orientation-dependent degradation of $Q$ near 90$^\\circ$ is associated with stronger transverse displacement near the inactive and anchor regions, resulting in enhanced energy leakage. These results reveal an orientation-dependent loss pathway in 128$^\\circ$Y-cut LN XBARs and provide design guidance for jointly optimizing $k^2$ and $Q$.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2606.16177",
  "author_total": 3,
  "authors": [
    {
      "name": "Byeongjin Kim"
    },
    {
      "name": "Ian Anderson"
    },
    {
      "name": "Ruochen Lu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/dgze6zvgca4rm.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2606.16177",
  "fulltext_url": null,
  "id": "dgze6zvgca4rm",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2606.16177",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "physics.app-ph"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2606.16177",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-05",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/dgze6zvgca4rm.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:01Z",
      "native_id": "2606.16177",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2606.16177"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.app-ph",
      "subfield": "applied-instrumentation"
    }
  ],
  "title": "In-Plane Q Anisotropy of Higher-Order XBARs in 128°Y-Cut Lithium Niobate",
  "title_text": "In-Plane Q Anisotropy of Higher-Order XBARs in 128°Y-Cut Lithium Niobate",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:01Z",
  "url": "https://research.draconitic.com/paper/dgze6zvgca4rm",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1109/tuson.2026.3737276",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}