{
  "abstract": "Heterogeneous integration combines complementary material properties in a single photonic platform. Here, we demonstrate on-chip $f$-2$f$ self-referencing in a heterogeneously integrated Si$_3$N$_4$/LiNbO$_3$ platform, in which supercontinuum generation in a Si$_3$N$_4$ waveguide and second-harmonic generation in a LiNbO$_3$ layer are spatially separated and linked by adiabatic escalator couplers. Pumped by a 1560 nm mode-locked laser with 75 pJ on-chip pulse energy, we detect the carrier-envelope offset frequency with 30 dB signal-to-noise ratio in 300 kHz resolution bandwidth. A comparative measurement confirms that the second harmonic originates in the LiNbO$_3$ layer and indicates opportunity for further improvements through periodic poling. These results establish heterogeneous Si$_3$N$_4$/LiNbO$_3$ integration as a viable building block for self-referenced ultrafast pulse sources in low-loss Si$_3$N$_4$ photonics.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.23328",
  "author_total": 7,
  "authors": [
    {
      "name": "Weichen Fan"
    },
    {
      "name": "Bastian Ruhnke"
    },
    {
      "name": "Camiel Op de Beeck"
    },
    {
      "name": "Giulio Tavani"
    },
    {
      "name": "Anton Vasiliev"
    },
    {
      "name": "Franz Kärtner"
    },
    {
      "name": "Tobias Herr"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bbt7qsydr41sm.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.23328",
  "fulltext_url": null,
  "id": "bbt7qsydr41sm",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.23328",
  "language": null,
  "licence": "CC-BY-SA-4.0",
  "licence_label": "CC BY-SA 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by-sa/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "physics.optics"
    ],
    [
      "openalex",
      "3107|Advanced Fiber Laser Technologies"
    ]
  ],
  "openalex": "W7214129311",
  "pdf_url": "https://arxiv.org/pdf/2609.23328",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-17",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bbt7qsydr41sm.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:30:52Z",
      "native_id": "2609.23328",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.23328"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.optics",
      "subfield": "optics-photonics"
    }
  ],
  "title": "$f$-2$f$ self-referencing for silicon nitride photonics via a heterogeneously integrated lithium niobate layer",
  "title_text": "f-2f self-referencing for silicon nitride photonics via a heterogeneously integrated lithium niobate layer",
  "type": "preprint",
  "updated_at": "2026-10-30T12:33:41Z",
  "url": "https://research.draconitic.com/paper/bbt7qsydr41sm",
  "venue": "arXiv",
  "versions": []
}