{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T20:04:14Z","timestamp":1789761854474,"version":"4.0.1"},"reference-count":41,"publisher":"Optica Publishing Group","issue":"19","license":[{"start":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T00:00:00Z","timestamp":1789689600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/doi.org\/10.1364\/OA_License_v2#VOR"},{"start":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T00:00:00Z","timestamp":1789689600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/opg.optica.org\/policies\/opg-tdm-policy.json"}],"funder":[{"name":"National Natural Science Foundation of China","award":["62305135"],"award-info":[{"award-number":["62305135"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Foreign Expert Project of Ministry of Human Resources and Social Security","award":["H20251011"],"award-info":[{"award-number":["H20251011"]}],"id":[{"id":"https:\/\/ror.org\/01kjwqy11","id-type":"ROR","asserted-by":"crossref"}]},{"name":"Postgraduate Research & Practice Innovation Program of Jiangsu Province","award":["26CXJH7330"],"award-info":[{"award-number":["26CXJH7330"]}]}],"content-domain":{"domain":["opg.optica.org"],"crossmark-restriction":false},"short-container-title":["Opt. Lett."],"published-print":{"date-parts":[[2026,10,1]]},"abstract":"<jats:p>\n                    Two-dimensional metal-halide perovskites have attracted considerable interest in nonlinear optics because of their large third-order nonlinear susceptibilities and strong light\u2013matter interactions. Momentum-mismatch-driven quasi-bound states in the continuum (quasi-BICs), characterized by high\n                    <jats:italic>Q<\/jats:italic>\n                    -factor and strong electromagnetic-field confinement, offer an effective route to enhancing third-harmonic generation (THG). Here, we utilize a momentum-mismatch-driven quasi-BIC grating based on two-dimensional perovskite (BA)\n                    <jats:sub>2<\/jats:sub>\n                    PbI\n                    <jats:sub>4<\/jats:sub>\n                    and establish the magnetic-dipole-dominated nature of its resonance through band structure,\n                    <jats:italic>Q<\/jats:italic>\n                    -factor, polarization, and multipole analyses. Under plane-wave excitation, we investigate THG enhancement by varying the width. Then we develop a Gaussian-beam excitation model using the angular-spectrum expansion method. Compared with plane-wave excitation, Gaussian-beam excitation yields a lower THG efficiency, because its finite angular spectrum excites off-\u0393 resonances with reduced\n                    <jats:italic>Q<\/jats:italic>\n                    -factors. Increasing the beam waist gradually restores the THG efficiency toward the plane-wave limit, reaching approximately 90% for beam waists above 165\u2009\u03bcm. These results clarify the impact of finite-width excitation on quasi-BIC-enhanced THG and provide guidance for experimental implementation.\n                  <\/jats:p>","DOI":"10.1364\/ol.613619","type":"journal-article","created":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T18:00:07Z","timestamp":1788285607000},"page":"5357","update-policy":"https:\/\/doi.org\/10.1364\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Enhanced third-harmonic generation efficiency of Gaussian beams in perovskite gratings supporting momentum-mismatch-driven quasi-bound states in the continuum"],"prefix":"10.1364","volume":"51","author":[{"given":"Hanchen","family":"Zhang","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00tyjp878","id-type":"ROR","asserted-by":"publisher"}]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Songchao","family":"Shen","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00tyjp878","id-type":"ROR","asserted-by":"publisher"}]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Runping","family":"Fang","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00tyjp878","id-type":"ROR","asserted-by":"publisher"}]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Huiyue","family":"Liang","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00tyjp878","id-type":"ROR","asserted-by":"publisher"}]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xu","family":"Jin","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00tyjp878","id-type":"ROR","asserted-by":"publisher"}]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yue","family":"Wu","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00tyjp878","id-type":"ROR","asserted-by":"publisher"}]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2140-9430","authenticated-orcid":true,"given":"Xiaoyan","family":"Chew","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00tyjp878","id-type":"ROR","asserted-by":"publisher"}]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ang","family":"Bian","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00tyjp878","id-type":"ROR","asserted-by":"publisher"}]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5677-7685","authenticated-orcid":true,"given":"Mohamed Farhat O.","family":"Hameed","sequence":"additional","affiliation":[{"name":"October Gardens"},{"name":"University of Mansoura"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2831-3821","authenticated-orcid":true,"given":"Jun","family":"Dai","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/00tyjp878","id-type":"ROR","asserted-by":"publisher"}]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"285","published-online":{"date-parts":[[2026,9,18]]},"reference":[{"key":"ol-51-19-5357-R1","doi-asserted-by":"publisher","first-page":"84","DOI":"10.1038\/s41377-025-02164-7","type":"journal-article","volume":"15","author":"Zhou","year":"2026","journal-title":"Light Sci. 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All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.","name":"copyright","label":"Copyright"}]}}