{"id":"e699ae99-69cb-4d38-b071-ef22930efb30","arxiv_id":"2506.20365","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"A multimode-fiber-based system generates toroidal optical beams with independently tunable temporal duration, aspect ratio, and OAM charge up to |l|=13.","lead":"The paper demonstrates a programmable system that generates 3D donut-shaped light beams carrying orbital angular momentum, and independently tunes their duration, size ratio, and twist. A multimode fiber delivers these beams through hard-to-reach places, which could aid imaging, sensing, and optical trapping.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Reported fidelity compares measured beams to simulations built from the same measured transmission matrix, so the gap to the intended ideal toroid is never quantified.","rationale":"The reader identified the self-referential quality metric as the weakest assumption, and I agree with that diagnosis. The sharper formulation is that the decisive missing quantity is the simulated-to-ideal overlap. The paper states the simulation is the best possible toroidal beam the experimental system can achieve, but never demonstrates that this best possible beam is actually close to the intended toroid. The 45-mode HG basis truncation is acknowledged to limit toroidal OAM to |l|<9 (Supp. Sec. 1), and the poloidal |l|=13 case uses roughly three phase samples per 2π, both of which can distort the simulated target before comparison to experiment. A straightforward numerical check would quantify this distortion. If the simulated-to-ideal overlap turns out high (above ~90%), the reader's concern is largely resolved and the paper stands as a conditional demonstration. If it is low, the central high-fidelity claim is overstated. The independence of duration, aspect ratio, and OAM is a related but secondary gap: the paper shows each parameter tuned while others are held constant, but no cross-parameter verification is provided. I would keep the verdict CONDITIONAL, because the needed analysis is well-defined and the experimental apparatus and methods are otherwise sound. No issues of fraud or internal inconsistency are present; the concern is about evidence completeness and the interpretation of the reported fidelity metric.","tokens_in":10268,"tokens_out":3898,"duration_ms":39413,"concrete_test":"Re-run the synthesis pipeline used for Figs. 2-5 and compute, for every displayed configuration, the magnitude-squared overlap between the 'Simulated' field (45-HG-mode target propagated by the measured TM) and the ideal toroidal beam before HG truncation and TM propagation, using the analytic target with the intended duration, aspect ratio, and OAM phase wrap. If any simulated-to-ideal overlap falls below ~90%, especially at |l|=13, 6.8 ps, or aspect ratios 1.54/2.70, then the reported measured-vs-simulated overlaps do not reliably measure fidelity to the intended beam, and the 'complete configurability' claim should be softened or supplemented with direct evidence of target accuracy.","verdict_should_be":"UNCHANGED","load_bearing_attack":"In §2.1, the quality metric |O|² is computed between the measured field and a 'Simulated' field obtained by constructing the target toroid as a 45-HG-mode superposition and propagating it with the experimentally measured TM. This makes the simulation the 'best possible' output of that same calibration, not an independent check of the intended beam. Two consequences follow: (i) if the TM has systematic errors, the simulation itself can deviate from the ideal toroid, and the reported overlaps (55-86%) are relative to that distorted target; (ii) the paper never reports the overlap between the Simulated field and the ideal toroidal beam defined by the stated duration, aspect ratio, and OAM charge. Without that number, 'high fidelity' remains unsupported: a 65% measured-vs-simulated overlap could correspond to a much lower overlap with the true target. The independence claim ('independent control of all physical and geometric properties') is also supported only by one-parameter-at-a-time examples; no data show, for instance, that changing OAM charge leaves duration and aspect ratio unchanged. A single missing analysis—reporting the simulated-to-ideal overlap—would distinguish a genuine fidelity measurement from a calibration-consistent check.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript reports an experimental platform for generating polarization-resolved spatiotemporal optical toroidal beams after propagation through a multimode fiber. The system combines a swept laser, a spectral pulse shaper, an SLM, and an MPLC to address 45 Hermite-Gaussian modes per polarization, and uses the measured transmission matrix to compute the input fields that produce the desired output beams. The authors demonstrate toroidal beams with temporal durations from 2.3 to 6.8 ps, toroidal aspect ratios from 1.5 to 2.7, poloidal OAM charges up to ±13, and toroidal OAM charges up to ±8. Fidelity is quantified by the overlap between the measured field and a simulated field obtained by propagating the target through the measured transmission matrix; reported overlaps range from 55% to 86%. The paper claims complete configurability and independent control of all physical and geometric properties of these beams.","tokens_in":10435,"tokens_out":8564,"duration_ms":81803,"significance":"If the central claims hold, this would be a valuable addition to the structured-light toolbox. The experimental system is a substantial engineering effort, and the range of demonstrated parameters — especially the combination of temporal shaping, polarization-resolved OAM, and delivery through an MMF — goes beyond prior toroidal-beam demonstrations. The use of the measured transmission matrix for both beam computation and validation is a coherent approach that ensures the reported fields are consistent with the system's calibration. However, the current fidelity metric does not directly support the 'high fidelity' and 'complete configurability' claims, since it compares the measurement to the system's own best possible output rather than to an ideal toroidal beam. The paper therefore needs a modest additional analysis to substantiate its headline claims, but the underlying experimental capability appears sound.","major_comments":[{"comment":"The quality metric |O|² is defined in §2.1 as the overlap between the measured field and a 'Simulated' field that is constructed by expressing the target toroid as a superposition of 45 Hermite-Gaussian modes and propagating it through the experimentally measured transmission matrix. The text explicitly states that this simulation 'provides the best possible toroidal beam the experimental system can achieve.' Consequently, the reported overlaps (55–86%) measure how closely the system reproduces its own calibrated output, not how close either field is to the ideal toroidal beam with the specified duration, aspect ratio, and OAM charge. The manuscript never reports the overlap between the simulated field and the ideal target. This matters because if the transmission matrix has systematic errors or the 45-mode basis truncates the target, the simulated field itself deviates from the ideal, and the reported overlaps could overstate the fidelity to the intended beam. I request an analysis that quantifies the simulated-to-ideal overlap for the configurations in Figs. 2–5 — for example, by comparing the simulated field to an analytic representation of the target toroid or to a higher-resolution numerical reference — and a presentation of the resulting end-to-end fidelity (e.g., as the product of measured-vs-simulated and simulated-vs-ideal overlaps). This is essential to support the abstract's 'high fidelity control' claim.","section":"§2.1, Figs. 2–5"},{"comment":"The abstract claims 'complete configurability of programmable, polarization-resolved OAM toroidal beams' and 'independent control of all physical and geometric properties,' and §3 states the system enables 'the ability to rapidly and independently fully configure beam duration, geometric structure and OAM charge.' The experimental demonstrations in Figs. 2–5, however, vary only one parameter at a time while holding the other two at fixed nominal values, and no data are presented showing simultaneous tuning of all three parameters or a quantitative cross-talk analysis (e.g., whether changing OAM charge preserves the measured duration and aspect ratio). The one-parameter sweeps are useful evidence, but they do not by themselves establish the independence and completeness claims. I request at least one demonstration of simultaneous variation of duration, aspect ratio, and OAM charge, together with a discussion of any inter-parameter constraints or trade-offs revealed by the measurements.","section":"Abstract and §3 (Discussion)"}],"minor_comments":[{"comment":"The caption contains a typo: 'respecitvely' should be 'respectively'.","section":"Fig. 1 caption"},{"comment":"The phrase 'have a minor and an aspect ratio of 2' is incomplete; presumably 'a minor radius' is intended, but please clarify whether the major radius or minor radius is meant.","section":"Fig. 4 caption"},{"comment":"The text states the system supports aspect ratios 'ranging from 1.54−2.74' while Fig. 3 and the surrounding text give the maximum as 2.70; please correct the inconsistency.","section":"§2.2"},{"comment":"The claimed '25,000 spatiotemporal and polarization degrees of freedom' is not derived in the text; with Nλ=293 and 90 modes per wavelength, the product is 26,370, so please clarify the counting or adjust the number.","section":"Abstract"},{"comment":"The manuscript says the 45-mode Hermite-Gaussian basis 'cannot generate a topological charge |l|>9 on the toroidal axis,' but the demonstrated maximum toroidal OAM is |l|=8; please explain why the practical limit is 8 rather than 9.","section":"§2.3"},{"comment":"The statement that the conjugate transpose of the transmission matrix 'allows us to calculate the required input field' is exact only for a unitary transmission matrix; please comment on the unitarity of the measured TM and the effect of modal losses.","section":"Methods §4.1"}],"recommendation":"major_revision","confidential_remarks":"This is a strong experimental paper with a clear and significant capability, but the fidelity metric needs to be strengthened before acceptance. The authors should be asked to provide the simulated-to-ideal overlap analysis and a demonstration of simultaneous parameter control. If the results are as claimed, the paper would be a good fit for physics.optics."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Dear colleague,\n\nThe headline is a real extension: the authors show independent programmability of duration, aspect ratio, and OAM for toroidal beams delivered through a multimode fiber. The work is careful and well documented. The key weakness is the fidelity metric—overlaps are computed against a simulation built from the same measured transmission matrix—so the distance to the ideal toroid is never quantified.\n\nCompared to their earlier paper (Ref. 18), which already demonstrated arbitrarily oriented, polarization-controlled toroidal beams through an MMF, the new contribution is independent tuning of temporal duration (2.3–6.8 ps), aspect ratio (1.5–2.7), and OAM (poloidal up to ±13, toroidal up to ±8). The experimental apparatus is described in detail, and the authors are honest about limits: quality degrades at longer durations and higher charges due to SLM pixel crosstalk and basis truncation.\n\nThe central flaw is the overlap metric. In Section 2.1, the simulated reference is generated by propagating the target through the experimentally measured TM. That makes the simulation the system's own best possible output, not an independent check. If the TM has systematic errors, the reference itself deviates from the intended beam, and a 65% measured-vs-simulated overlap could mean a much lower overlap with the true target. The paper never reports the simulated-to-ideal overlap, so \"high fidelity\" is not fully supported. This is a real but non-fatal weakness: the capability is demonstrated convincingly, but the fidelity claim is overstated.\n\nTwo minor issues: no error bars or repeatability data, and the \"independence\" of control knobs is shown only one-at-a-time—no figure shows that changing OAM leaves duration and aspect ratio unchanged. Data availability is \"upon request,\" which is weak.\n\nThis paper is useful for anyone working on spatiotemporal structured light, OAM beams, or fiber delivery of complex fields. It is an incremental but solid advance over Ref. 18. With a request for simulated-to-ideal overlap, error bars, and ideally a joint-variation test, it deserves serious peer review. I would engage with it.","headline":"Independent tuning of duration, aspect ratio, and OAM is real, but the fidelity metric is self-referential and the ideal-target overlap is never reported.","tokens_in":10989,"tokens_out":4765,"would_cite":true,"duration_ms":45592,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"A programmable platform generates 3D toroidal light beams with independently tunable duration, geometry, and OAM charge after propagation through a multimode fiber.","keywords":["toroidal beams","spatiotemporal light fields","orbital angular momentum","multimode fiber","transmission matrix","structured light","polarization control","beam shaping"],"falsifier":"Measure the output field of one of the extreme configurations (for example, aspect ratio 1.54 or $|l|=13$) and decompose it in a mode basis larger than the 45-mode Hermite-Gaussian set used in the paper; if a substantial fraction of the power lies outside the 45-mode subspace, or if an independently defined analytic toroidal beam produces a markedly lower overlap than the reported metric, the claim of complete configurability would be weakened. Alternatively, re-measure the transmission matrix after the experiment and check whether the same input still produces the same output.","tokens_in":10065,"feed_emoji":"🍩","tokens_out":7125,"duration_ms":64764,"temperature":0.7,"pith_summary":"This paper demonstrates a fully programmable platform for generating spatiotemporal toroidal optical beams—three-dimensional donut-shaped pulses of light that carry orbital angular momentum—after they have propagated through a multimode optical fiber. The authors show independent control of three properties that were previously coupled: temporal duration (2.3–6.8 ps), toroidal aspect ratio (1.5–2.7), and OAM topological charge (up to $|l|=13$ for poloidal phase wraps and $|l|=8$ for toroidal phase wraps), for both polarization states simultaneously. This matters because applications in quantum entanglement, imaging, sensing, and optical manipulation require beams whose timing, shape, and twist can each be tuned without disturbing the others. If the claim is correct, the result is a complete spatiotemporal beam-shaping toolbox that can also deliver these beams into hard-to-reach places through the fiber.","feed_headline":"Toroidal beams: duration, shape, and OAM independently tunable","feed_subtitle":"A 90-mode fiber delivers fully programmable 3D toroidal light beams for quantum, imaging, and manipulation applications.","key_machinery":"The load-bearing mechanism is a spectral pulse shaper paired with a multi-plane light converter that generates, for each of 293 wavelength channels, any amplitude-and-phase superposition of 45 orthogonal Hermite-Gaussian modes per polarization, coupled into a 90-mode graded-index multimode fiber. A spectrally resolved linear transmission matrix of the fiber is measured once; the conjugate transpose of this matrix converts a desired output toroidal beam—defined as a sequence of two-dimensional temporal cross-sections carrying either poloidal or toroidal phase wraps—into the input field that produces it at the fiber output. The same transmission matrix is then used numerically to propagate the targeted beam for comparison, and the magnitude-squared overlap between measured and simulated fields serves as the fidelity metric.","core_discovery":"On the paper's own terms, the central discovery is that complete configurability of spatiotemporal OAM toroidal beams is achievable after propagation through a multimode fiber supporting 90 spatial/polarization modes, using the system's 25,000 spatiotemporal and polarization degrees of freedom. Each beam is synthesized as a superposition of 45 Hermite-Gaussian modes per polarization per spectral channel, and the required input field is computed from the conjugate transpose of the experimentally measured spectrally resolved transmission matrix. This enables independent adjustment of temporal duration, the ratio of major to minor torus radius, and the OAM charge imparted by either poloidal or toroidal phase wraps. The authors report amplitude-phase-polarization overlaps between experimental and simulated beams of 55–86% across the tested parameter ranges.","pith_inferences":["The quality metric is self-referential: the 'Simulated' comparison beam is produced by propagating the target through the same measured transmission matrix that shaped the experimental beam, so the reported overlaps characterize reproducibility of the fiber system rather than absolute fidelity to an ideal toroidal beam.","Because the toroidal OAM limit of $|l|=8$ is set by the 45-mode Hermite-Gaussian basis, increasing the basis size should directly extend the achievable toroidal charge, making the platform's range a function of mode count rather than a fundamental physics limit.","Independent tunability across duration, geometry, and OAM could let experiments isolate how each property individually affects light-matter interactions such as trapping or ionization, something that is difficult when the properties are coupled.","A dynamic re-measurement of the transmission matrix would extend the same architecture to adapting to changing or moving scattering media, potentially enabling real-time re-routing of toroidal beams."],"forward_implications":["Toroidal beams can be reprogrammed on demand through the spatial light modulator, with no physical reconfiguration of the apparatus.","Independent control of duration, aspect ratio, OAM, and polarization enables beam tailoring for high-dimensional quantum entanglement, optical manipulation, and sensing.","Because the beams are delivered through a multimode fiber, they can reach previously inaccessible regions, such as the interior of scattering biological tissue.","The same platform could generate time-varying OAM beams on the picosecond timescale, extending demonstrations currently limited to microwaves, extreme ultraviolet, and femtosecond near-infrared light."],"supporting_citations":[{"why":"Supplies the prior demonstration of toroidal beams with arbitrary polarization and orientation through a multimode fiber, the method this work extends.","marker":"[18]"},{"why":"Establishes the vector spatiotemporal field generation technique through the spectral pulse shaper and multi-plane light converter.","marker":"[19]"},{"why":"Introduces the transmission matrix measurement approach used to calibrate the system.","marker":"[45]"},{"why":"Provides the conjugate-transpose-based method for computing input fields that produce desired outputs through the transmission matrix.","marker":"[46]"},{"why":"Defines toroidal vortices of light and the poloidal/toroidal OAM phase-wrap encodings that the beams here carry.","marker":"[10]"},{"why":"Supplies the phase-sampling criterion that sets the OAM charge limit for the poloidal wraps.","marker":"[36]"}],"fun_headline_variants":["Fiber enables full control of 3D toroidal OAM beams","25,000 degrees of freedom shape toroidal light beams","Independent duration, shape, OAM control in toroidal beams","Multimode fiber makes toroidal OAM beams fully programmable","Programmable toroidal beams: duration, shape, OAM"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The reported fidelity assumes that the experimentally measured transmission matrix, used both to compute the input fields and to generate the 'Simulated' reference beam for comparison, is accurate and stable, and that the 45-mode Hermite-Gaussian basis is sufficient to represent the target toroidal beams.","fun_headline_variants_meta":{"raw":{"variants":["Fiber enables full control of 3D toroidal OAM beams","25,000 degrees of freedom shape toroidal light beams","Independent duration, shape, OAM control in toroidal beams","Multimode fiber makes toroidal OAM beams fully programmable","Programmable toroidal beams: duration, shape, OAM"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000632,"raw_usage":{"total_tokens":2909,"prompt_tokens":926,"completion_tokens":1983,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":542,"completion_tokens_details":{"reasoning_tokens":1896}},"tokens_in":542,"tokens_out":1983,"duration_ms":15222,"temperature":1.0,"reasoning_tokens":1896,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-06T22:48:46.752605+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Measure the output field of one of the extreme configurations (for example, aspect ratio 1.54 or $|l|=13$) and decompose it in a mode basis larger than the 45-mode Hermite-Gaussian set used in the paper; if a substantial fraction of the power lies outside the 45-mode subspace, or if an independently defined analytic toroidal beam produces a markedly lower overlap than the reported metric, the claim of complete configurability would be weakened. Alternatively, re-measure the transmission matrix after the experiment and check whether the same input still produces the same output.","supporting_citations":[{"cited_title":"Spatiotemporal toroidal light beams with arbitrary polarization and orientation through a multimode fiber","cited_arxiv_id":"2501.13246","evidence_quote":"Supplies the prior demonstration of toroidal beams with arbitrary polarization and orientation through a multimode fiber, the method this work extends."},{"cited_title":"Nature Communications11(1), 5813 (2020) https://doi.org/10.1038/s41467-020-19601-3","cited_arxiv_id":null,"evidence_quote":"Establishes the vector spatiotemporal field generation technique through the spectral pulse shaper and multi-plane light converter."},{"cited_title":"Physical Review Letters104(10), 100601 (2010) https://doi.org/10.1103/PhysRevLett.104.100601","cited_arxiv_id":null,"evidence_quote":"Introduces the transmission matrix measurement approach used to calibrate the system."},{"cited_title":"Physical Review Letters 116(25), 253901 (2016) https://doi.org/10.1103/PhysRevLett.116.253901 17","cited_arxiv_id":null,"evidence_quote":"Provides the conjugate-transpose-based method for computing input fields that produce desired outputs through the transmission matrix."},{"cited_title":"Nature Photonics16(7), 519–522 (2022) https://doi.org/10.1038/s41566-022-01013-y","cited_arxiv_id":null,"evidence_quote":"Defines toroidal vortices of light and the poloidal/toroidal OAM phase-wrap encodings that the beams here carry."},{"cited_title":"Optics Express27(5), 6459 (2019) https://doi.org/10","cited_arxiv_id":null,"evidence_quote":"Supplies the phase-sampling criterion that sets the OAM charge limit for the poloidal wraps."}],"review_version":1}