{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,4]],"date-time":"2026-05-04T09:38:52Z","timestamp":1777887532568,"version":"3.51.4"},"reference-count":43,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T00:00:00Z","timestamp":1777420800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Key Research and Development Program of China","award":["2023YFB4604400"],"award-info":[{"award-number":["2023YFB4604400"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Micromachines"],"abstract":"<jats:p>In this work, we report the realization of curved distributed Bragg reflectors (DBRs) without the need for lithography to achieve strong lateral confinement in a GaN-based vertical cavity. By embedding SiO2 nanospheres during deposition, curved DBRs with a funnel-shaped cross-section were fabricated. Based on the formed curved DBRs, a vertical cavity with a quality factor exceeding 2800 and a mode volume below 0.14 \u03bcm3 was successfully fabricated. The optical pumping threshold power of a vertical cavity surface-emitting laser (VCSEL) with a curved DBR was reduced to 76 nW, which is one order of magnitude lower than that of the same VCSEL with double-planar DBRs. Near-field patterns revealed that the curved-DBR VCSEL emits a circularly symmetric TEM00 mode with a full width at half maximum (FWHM) of only 1.8 \u03bcm. We believe this is an effective technique for fabricating low-threshold or small-aperture VCSELs.<\/jats:p>","DOI":"10.3390\/mi17050544","type":"journal-article","created":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T09:46:11Z","timestamp":1777455971000},"page":"544","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Strong Lateral Mode Confinement by Embedding SiO2 Nanospheres in the DBRs of GaN-Based VCSELs"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8241-8165","authenticated-orcid":false,"given":"Huanqing","family":"Chen","sequence":"first","affiliation":[{"name":"State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Menglai","family":"Lei","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Linghai","family":"Meng","sequence":"additional","affiliation":[{"name":"Guangxi Hurricane Chip Technology Co., Ltd., Guangxi 545003, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zihao","family":"Chu","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Weihua","family":"Chen","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiaodong","family":"Hu","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,4,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1845","DOI":"10.1109\/3.7126","article-title":"Surface Emitting Semiconductor Lasers","volume":"24","author":"Iga","year":"1988","journal-title":"IEEE J. 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