{
  "annotation_id": "0c7cad38-a4f3-42a7-9412-aa6e976af417",
  "date_created": "2026-03-02T18:00:59.932000Z",
  "date_modified": "2026-03-02T18:00:59.932000Z",
  "file_hash": "7656a0963e28599ca3eba468ce575433bfa399ac9ff81745f9bdbc70eec76f7c",
  "private": false,
  "record": {
    "abstract": "There exists a class of realizable, active media for which the refractive\nindex cannot be defined as an analytic function in the upper half-plane of\ncomplex frequency. The conventional definition of the refractive index based on\nanalyticity is modified such that it is valid for active media in general, and\nassociated Fresnel equations are proved. In certain active media, the presence\nof a ``backward\u0027\u0027 wave, for which both phase velocity and Poynting\u0027s vector\npoint towards the excitation source, is demonstrated.",
    "arxiv_id": "physics/0509112",
    "authors": [
      "Johannes Skaar"
    ],
    "categories": [
      "physics.optics"
    ],
    "doi": "10.1103/PhysRevE.73.026605",
    "journal_ref": "Phys. Rev. E 73, 026605 (2006)",
    "title": "Fresnel equations and the refractive index of active media",
    "url": "https://arxiv.org/abs/physics/0509112"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "6a8736e3-b5a1-418f-9354-7b6ceadf8c64",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}