{
  "abstract": "Recent demonstrations of unidirectional imaging using diffractive multilayers have brought a concept akin to optical isolation to imaging, yet the fundamental limits of such asymmetry have remained unknown. Here we develop a general theory of asymmetric imaging in linear, passive, reciprocal optical systems and derive a fundamental bound on the achievable unidirectionality. Reciprocity requires the forward and reverse transmission operators to have identical singular values, a wave-optical analogue of étendue equality, with a simple consequence: perfect asymmetry is attainable only for sets of $M \\leq N/2$ orthogonal object patterns, where $N$ is the number of available object/image modes; for $M > N/2$, the average power asymmetry is bounded by $(N-M)/M$. Guided by this result, we present two complementary realizations: refractive imaging systems formed by bulk lenses and stops that attain the half-occupation limit, and a 1 cm-diameter all-silicon metasurface doublet that exhibits asymmetric focusing at 4 $μ$m while fully complying with Lorentz reciprocity. We fabricate the doublet by direct laser writing and experimentally demonstrate its focusing asymmetry. By establishing mechanism-independent limits, our results provide a benchmark and design principle for asymmetric imaging across platforms, with implications for defense, surveillance and secure communications.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.36350",
  "author_total": 9,
  "authors": [
    {
      "name": "Romil Audhkhasi"
    },
    {
      "name": "Anna Wirth-Singh"
    },
    {
      "name": "Rose Johnson"
    },
    {
      "name": "Maksym Zhelyeznyakov"
    },
    {
      "name": "Vladimir Yarmolik"
    },
    {
      "name": "Rafael Piestun"
    },
    {
      "name": "Andrea Alù"
    },
    {
      "name": "Arka Majumdar"
    },
    {
      "name": "Owen Miller"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bzn1kr0qasfzs.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.36350",
  "fulltext_url": null,
  "id": "bzn1kr0qasfzs",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.36350",
  "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"
    ],
    [
      "arxiv",
      "physics.optics"
    ],
    [
      "openalex",
      "2504|Metamaterials and Metasurfaces Applications"
    ]
  ],
  "openalex": "W7214942805",
  "pdf_url": "https://arxiv.org/pdf/2609.36350",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-28",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bzn1kr0qasfzs.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:31Z",
      "native_id": "2609.36350",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.36350"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.app-ph",
      "subfield": "applied-instrumentation"
    },
    {
      "field": "physics",
      "origin": "arxiv:physics.optics",
      "subfield": "optics-photonics"
    }
  ],
  "title": "Asymmetric imaging: Reciprocity bounds and manifestations",
  "title_text": "Asymmetric imaging: Reciprocity bounds and manifestations",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:31Z",
  "url": "https://research.draconitic.com/paper/bzn1kr0qasfzs",
  "venue": "arXiv",
  "versions": []
}