{"paper":{"title":"Quantitative Pulse Shape-Instability Analysis Using 2D-Runs FROG","license":"http://creativecommons.org/licenses/by-nc-sa/4.0/","headline":"A two-dimensional runs test applied to differences between measured and retrieved FROG traces yields a parameter R that quantifies pulse-shape instability in a train.","cross_cats":["physics.atom-ph"],"primary_cat":"physics.optics","authors_text":"Abinash Das, Bilol Banerjee, E. P. Duchrist Crews, Pedram Abdolghader, Rana Jafari, Rick Trebino","submitted_at":"2026-04-27T11:51:52Z","abstract_excerpt":"We present a method for quantifying pulse-shape instability in a train of pulses using multi-shot Second-Harmonic-Generation Frequency-Resolved Optical Gating (SHG FROG). All versions of multi-shot FROG have previously shown the ability to distinguish stable from unstable pulse trains, as systematic differences appear between measured and retrieved traces when instability is present. This has proved possible because the recently introduced Retrieved-Amplitude N-grid Algorithmic (RANA) approach provides highly reliable pulse retrieval, even for unstable pulse trains and in the presence of noise"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"We now introduce an instability parameter, R. It involves the use of the well-known statistical Runs test... extended to two dimensions to enumerate 2D runs hills and valleys in the difference between measured and retrieved 2D FROG traces.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"That non-random discrepancies between measured and retrieved FROG traces are caused by physical pulse-shape instability rather than algorithmic stagnation or other artifacts, which rests on the prior claim that the RANA algorithm remains highly reliable for unstable trains.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"A 2D extension of the statistical runs test defines an instability parameter R from systematic discrepancies in multi-shot SHG FROG traces after reliable RANA retrieval.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"A two-dimensional runs test applied to differences between measured and retrieved FROG traces yields a parameter R that quantifies pulse-shape instability in a train.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"8df5e63c44705166fdaee61e4c7ab35060cbc537a76707f758f52fe56c1d68f3"},"source":{"id":"2604.24359","kind":"arxiv","version":1},"verdict":{"id":"711078f4-6879-4db2-a47a-d2763bf3c71c","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-08T01:59:30.599064Z","strongest_claim":"We now introduce an instability parameter, R. It involves the use of the well-known statistical Runs test... extended to two dimensions to enumerate 2D runs hills and valleys in the difference between measured and retrieved 2D FROG traces.","one_line_summary":"A 2D extension of the statistical runs test defines an instability parameter R from systematic discrepancies in multi-shot SHG FROG traces after reliable RANA retrieval.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"That non-random discrepancies between measured and retrieved FROG traces are caused by physical pulse-shape instability rather than algorithmic stagnation or other artifacts, which rests on the prior claim that the RANA algorithm remains highly reliable for unstable trains.","pith_extraction_headline":"A two-dimensional runs test applied to differences between measured and retrieved FROG traces yields a parameter R that quantifies pulse-shape instability in a train."},"integrity":{"clean":false,"summary":{"advisory":0,"critical":1,"by_detector":{"doi_compliance":{"total":1,"advisory":0,"critical":1,"informational":0}},"informational":0},"endpoint":"/pith/2604.24359/integrity.json","findings":[{"note":"Identifier '10.1016/0010-4018(92)90070-8' is syntactically valid but the DOI registry (doi.org) returned 404, and Crossref / OpenAlex / internal corpus also have no record. 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Lett. 1 January 1965; 6 (1): 6–8. https://doi.org/10.1063/1.1754124","work_id":"d357faa7-b80c-44ed-8552-282d62cc30be","ref_index":1,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1063/1.1754025","year":1964,"title":"L. E. Hargrove, R. L. Fork, M. A. Pollack; Locking of he–ne laser modes induced by synchronous intracavity modulation. Appl. Phys. Lett. 1 July 1964; 5 (1): 4–5. https://doi.org/10.1063/1.1754025","work_id":"40e78fbf-93e7-4041-81e8-acdcd2bc118d","ref_index":2,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1063/1.1713999","year":1965,"title":"Amnon Yariv; Internal Modulation in Multimode Laser Oscillators. J. Appl. Phys. 1 February 1965; 36 (2): 388 –391. https://doi.org/10.1063/1.1713999","work_id":"595fb5ee-398e-4cac-9da7-70873eb0762f","ref_index":3,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1364/ol.19.001149","year":1994,"title":"Pulse evolution in a broad-bandwidth Ti:sapphire laser","work_id":"96f881da-2076-415c-9421-2ff7ea49a0a3","ref_index":4,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1364/ol.21.001493","year":1996,"title":"Sub-10-fs operation of Kerr-lens mode-locked lasers","work_id":"31bab3ec-898b-4f73-a338-1bad4be0930a","ref_index":5,"cited_arxiv_id":"","is_internal_anchor":false}],"resolved_work":69,"snapshot_sha256":"e55983a8fafb96bcebe12d3896a9f59e87b1749c44430b8536b121a1ebd1ff56","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}