{
  "abstract": "Broadband lasers suppress the absolute two-plasmon-decay instability that preheats inertial-fusion targets. The usual scaling relates this suppression to the drive's coherence time, a power-spectrum statistic insensitive to spectral phase. By gradient descent through a differentiable enveloped wave solver, we show that at fixed power spectrum phase optimization raises the threshold from the random-phase median of $2.8\\,I_\\mathrm{mono}$ to $4.1\\,I_\\mathrm{mono}$, but produces a transform-limited (TL) pulse train with peak-to-average ratio $R=32$. Joint amplitude--phase optimization reaches $5.6\\,I_\\mathrm{mono}$ at $R=3.6$, above the best tested TL line-count result of $4.5\\,I_\\mathrm{mono}$ at $R=16$; relaxing the peak constraint raises the joint threshold to $6.4\\,I_\\mathrm{mono}$. An exact growth-rate budget evaluated inside the simulation separates the two mechanisms. TL suppresses coupling mainly by concentrating the pump field into short bursts, thereby lowering its time-averaged magnitude at fixed average intensity. The joint optima retain near-random values of this amplitude measure while suppressing both the available coupling and the fraction realized through pump--daughter alignment. The advantage of joint optimization persists from $1\\%$ to $4\\%$ bandwidth and from OMEGA-scale to ignition-scale conditions.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.31942",
  "author_total": 4,
  "authors": [
    {
      "name": "A. S. Joglekar"
    },
    {
      "name": "R. K. Follett"
    },
    {
      "name": "D. H. Froula"
    },
    {
      "name": "J. P. Palastro"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3tv59cm0m0bn3.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.31942",
  "fulltext_url": null,
  "id": "3tv59cm0m0bn3",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.31942",
  "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.optics"
    ],
    [
      "arxiv",
      "physics.plasm-ph"
    ],
    [
      "openalex",
      "3106|Laser-Plasma Interactions and Diagnostics"
    ]
  ],
  "openalex": "W7214702807",
  "pdf_url": "https://arxiv.org/pdf/2609.31942",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-29",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3tv59cm0m0bn3.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:48Z",
      "native_id": "2609.31942",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.31942"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.optics",
      "subfield": "optics-photonics"
    },
    {
      "field": "physics",
      "origin": "arxiv:physics.plasm-ph",
      "subfield": "plasma"
    }
  ],
  "title": "Joint Amplitude-Phase Optimization of Broadband Lasers Raises Absolute Two-Plasmon-Decay Thresholds Above Coherence-Time Predictions",
  "title_text": "Joint Amplitude-Phase Optimization of Broadband Lasers Raises Absolute Two-Plasmon-Decay Thresholds Above Coherence-Time Predictions",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:48Z",
  "url": "https://research.draconitic.com/paper/3tv59cm0m0bn3",
  "venue": "arXiv",
  "versions": []
}