Pith. sign in

REVIEW 3 major objections 5 minor 40 references

Tunable megawatt-scale sub-20 fs visible pulses from a fiber laser source

T0 review · 3 major / 5 minor · reviewed 2026-08-09 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗ Review JSON

Pith's one-line read A fiber oscillator plus gas-filled hollow-core fiber produces tunable sub-20 fs visible pulses with up to 39 nJ energy and 2.2 MW peak power.

desk verdict A credible but incremental fiber-based route to tunable visible femtosecond pulses; the 13 fs headline rests on a FROG grid too coarse to trust without more evidence. read the letter →

arxiv 2502.01322 v2 pith:2SIN5YQY submitted 2025-02-03 physics.optics

Mohammed Sabbah , Robbie Mears , Leah R. Murphy , Kerrianne Harrington , James M. Stone , Tim A. Birks , John C. Travers This is my paper · ORCID
classification physics.optics PACS 42.65.Wi42.65.Re
keywords ultrafastlaserpulsesresonantdispersive-waveemissiongain-managednonlinearamplificationhollow-coreantiresonantfibervisiblepulsegenerationcompressionfrequency-resolvedopticalgating
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

This paper sets out to show that a fiber-laser-based system can replace the bulky, expensive Ti:sapphire and optical-parametric-amplifier chains normally used for tunable ultrafast visible pulses. The authors combine a gain-managed nonlinear amplifier (GMNA) with resonant dispersive-wave (RDW) emission in a gas-filled hollow-core antiresonant fiber, and report sub-20 fs pulses tunable from about 400 nm to beyond 700 nm, with energies up to 39 nJ and peak powers exceeding 2 MW at 4.8 MHz. If correct, this turns a technique previously tied to amplified solid-state pump lasers into a compact, modest-cost source suitable for multiphoton imaging and ultrafast spectroscopy. The central result is that the shortest measured pulse is 13 fs, with more than 81% of its energy in the main peak.

What carries the argument

Two mechanisms carry the argument. Gain-managed nonlinear amplification is an over-extended self-similar amplifier: a narrowband low-energy seed is amplified in a Yb-doped fiber whose longitudinally varying, gain-saturated nonlinear dynamics broaden the spectrum into a near-linear chirp, so a simple grating pair compresses it to 38 fs at ~10 MW. Resonant dispersive-wave emission is the phase-matched transfer of energy from a soliton to a linear (dispersive) wave in the presence of high-order dispersion; tuning the argon pressure shifts the phase-matching wavelength, and the antiresonant hollow-core fiber's transmission band is chosen so no high-loss resonance sits between pump and RDW, raising conversion efficiency to 13%.

What would settle it

Run an independent autocorrelation or direct spectral-phase measurement on the compressed RDW pulse at 40 bar and check whether the retrieved 13 fs FWHM and 2.2 MW peak power are reproduced; also measure the BBO crystal's phase-matching acceptance across the full RDW spectrum to ensure sidebands are not being filtered.

Watch

Extended reading notes

Core claim

The paper demonstrates that resonant dispersive-wave emission can be pumped directly by a fiber oscillator plus GMNA rather than by an amplified Ti:sapphire or Yb system. A 38 fs, ~10 MW compressed GMNA pulse at 520 nJ drives a 35 cm antiresonant hollow-core fiber filled with argon; varying the gas pressure from 20 to 75 bar tunes the RDW from roughly 400 nm to beyond 700 nm. At 40 bar, spectral filtering and chirped-mirror compression yield a retrieved 13 fs FWHM pulse with 39 nJ energy and an estimated 2.2 MW peak power, and pulses at 520, 576, and 660 nm are all measured under 20 fs. The RDW carries up to 13% of the coupled pump energy, exits in a fundamental-mode beam, and the system runs for tens of hours with 0.8% relative intensity noise. The authors argue this gives comparable or better pulse duration, tunability, and peak power than Ti:sapphire or OPA sources at a fraction of the complexity.

Load-bearing premise

The quoted 13 fs duration and 2.2 MW peak power rest entirely on the SHG-FROG retrieval, which reports only a 0.8% retrieval error and no independent autocorrelation or uncertainty analysis, so a bias in the BBO crystal phase-matching bandwidth, spectral calibration, or background subtraction would change the headline numbers.

Editorial extensions

If this is right

  • A single fiber-based source can deliver sub-20 fs pulses at megawatt peak power across the visible, a regime previously requiring Ti:sapphire amplifiers or optical parametric amplifiers.
  • Tuning is achieved by changing gas pressure in the hollow-core fiber, which is simpler and faster than replacing nonlinear crystals or adjusting OPA stages.
  • At the demonstrated 4.8 MHz repetition rate and ~39 nJ energies, the source is directly relevant to multiphoton microscopy and time-resolved visible spectroscopy.
  • Because the GMNA output is 38 fs and ~10 MW, it can drive RDW generation without a separate temporal compression stage.
  • The documented tens-of-hours stability and 0.8% relative intensity noise make the system plausible for extended hands-off operation in application labs.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • A natural next test is to pump the same architecture with a Mamyshev oscillator or standard step-index gain fiber, trading some peak power for a substantially lower-cost, fully fiber-integrated system.
  • Frequency-doubling the GMNA pump to the green, as the authors note, could drive deep-ultraviolet RDW emission below 400 nm with the same compact footprint, extending the source's range.
  • If the FROG retrieval is confirmed by an independent autocorrelation, the architecture becomes a credible candidate for a commercial turnkey source; if not, the headline 13 fs and 2.2 MW numbers would need revision.
  • Filling the fiber with a Raman-active gas could add soliton self-frequency shifting, letting one fiber-based device span from the deep UV to the infrared, but that extension is speculative without demonstration.
Share X Bluesky LinkedIn Reddit HN

Signed reviews

No signed human review yet.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

3 major / 5 minor

Summary. The paper reports a compact fiber-laser source that combines gain-managed nonlinear amplification (GMNA) with resonant dispersive-wave (RDW) emission in a gas-filled antiresonant hollow-core fiber. The authors claim sub-20 fs pulses tunable from approximately 400 nm to beyond 700 nm, with energies up to 39 nJ and peak powers up to 2.2 MW at 4.8 MHz repetition rate. The system comprises a NALM oscillator, a pre-amplifier, a GMNA stage, and an RDW stage, with argon pressure used to tune the RDW wavelength. Temporal characterization is performed with all-reflection SHG-FROG, and spectra are calibrated with NIST-traceable lamps. The paper also reports stability measurements over tens of hours and a relative intensity noise of 0.8%.

Significance. If the quantitative claims are fully supported, this is a valuable demonstration: a relatively simple and compact fiber-based source reaching few-femtosecond-scale, tunable visible pulses with megawatt peak power would offer a credible alternative to more complex Ti:sapphire and optical parametric amplifier systems for applications such as multiphoton imaging and ultrafast spectroscopy. The manuscript has notable strengths: the RDW tuning data are presented over a wide range, the spectral calibration is described, the FROG retrieval error is reported as 0.8%, and stability data are included. However, the central pulse-duration and peak-power claims currently rest on a FROG measurement whose delay sampling appears too coarse to resolve a 13 fs pulse, and no uncertainty analysis is provided for the headline numbers. These issues must be addressed before the claims can be considered fully established.

major comments (3)
  1. [Fig. 4 and accompanying SHG-FROG text] The headline 13 fs duration and 2.2 MW peak power rest entirely on the SHG-FROG retrieval in Fig. 4, but the trace is sampled on a 512×40 grid over a −500 to +500 fs delay window, i.e. approximately 25 fs steps. For a 13 fs pulse the SHG-FROG temporal feature has an intensity-autocorrelation width of only about 18–25 fs, so the central feature is sampled by at most one or two delay points. A 0.8% retrieval error on such a coarse grid does not establish uniqueness; many different pulse shapes can fit the same sparsely sampled trace. The authors should provide a finer-delay FROG measurement or an independent temporal characterization (e.g., autocorrelation or SPIDER), demonstrate retrieval stability with respect to grid spacing, and report the resulting uncertainty on the retrieved duration and peak power, including the effect of the 10 µm type-I BBO phase-matching bandwidth and the background-subtraction procedure.
  2. [Abstract and Fig. 3] The abstract claims 'sub-20 femtosecond pulses tunable from 400 nm to beyond 700 nm,' but temporal characterization is reported only at 520, 576, and 660 nm (Fig. 3b–d) and for the compressed pulse in Fig. 4. No pulse duration is measured across the rest of the tuning range, and the text itself states that beyond 700 nm the RDW 'does not cleanly separate from the pump pulse, instead it forms part of a supercontinuum.' The sub-20 fs tunability claim should be restricted to the wavelengths actually characterized, or additional temporal measurements across the full range should be provided.
  3. [Energy and peak-power reporting] The manuscript reports 39 nJ and 2.2 MW without uncertainties. The RDW energy is extracted from calibrated spectra and 'validated using a power meter,' but no calibration uncertainty, reproducibility, or systematic-error analysis is given. The peak power depends on both the FROG-retrieved 13 fs duration and the assumed 81% energy fraction in the main peak, so these sources of uncertainty should be propagated into the headline values or the dominant systematic errors should be stated explicitly.
minor comments (5)
  1. [RDW compression description] The text says an '850 nm long-pass filter' is used to separate the visible RDW from the pump; a long-pass filter at 850 nm would reject the 400–700 nm RDW and transmit the ~1030 nm pump. If a short-pass filter was intended, please correct this.
  2. [Fig. 4 caption and text] The central wavelength and gas pressure of the compressed pulse characterized in Fig. 4 are not stated in the text; please give these values to allow direct comparison with the 520, 576, and 660 nm measurements in Fig. 3.
  3. [Main-pulse energy fraction definitions] The statements 'more than 75% of the pulse energy concentrated in the main pulse' (GMNA) and 'more than 81% of the energy located within the main peak' (RDW) need a precise definition of how the main pulse is separated from the pedestal or background, since this directly affects the peak-power estimate.
  4. [Fig. 3(a) normalization] Please clarify whether the spectra in Fig. 3(a) are individually normalized or shown on a common intensity scale; the separate energy axis makes the current plotting convention ambiguous.
  5. [FROG grid convention] Please clarify the FROG grid convention: if the delay axis has only 40 points over ±500 fs, how is the 512-point axis distributed, and what delay step was actually used? This is important for assessing the temporal resolution of the retrieval.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the generation chain (GMNA + RDW) uses externally established theory and independently measured spectra/FROG traces.

full rationale

The paper's derivation chain is not circular. The GMNA pump is characterized by measured spectra and an independently retrieved SHG-FROG trace (Fig. 2), and the RDW stage is tuned by argon pressure using the standard phase-matching condition cited to prior non-self work [10,35]. The central headline values (13 fs, 39 nJ, 2.2 MW) come from calibrated spectral and power measurements and an all-reflection SHG-FROG retrieval with 0.8% error against the measured trace (Fig. 4); they are not used as inputs to any model that then 'predicts' them. Self-citations (refs [19], [38]) appear only as supporting context for future extensions or prior demonstrations, not as load-bearing justifications for the current claim. The coarse 40-step FROG delay grid is a measurement-resolution concern, but it is not an instance of circular reasoning: the reported duration is not a fitted parameter in the generation model. Therefore no step reduces by construction to its own inputs.

Assumptions & free parameters 0 free parameters · 5 assumptions · 0 invented entities

No new free parameters are fitted to data: the source is a physical system characterized by calibrated spectra and FROG. The central claim rests on established RDW/GMNA theory, the antiresonance model, and the FROG reconstruction assumption; none of these are ad hoc inventions of this paper.

assumptions (5)
  • domain assumption RDW phase matching in gas-filled hollow-core fiber is described by the established soliton-to-dispersive-wave resonance condition, so tuning gas pressure tunes the emitted wavelength.
    Invoked to explain tuning from 400 to 700 nm by argon pressure; no derivation in this paper, references [9, 10, 15, 35].
  • domain assumption The antiresonance model correctly predicts the fundamental guidance band and low loss for both pump and visible spectral regions in the 36 micrometer core, 150 nm wall fiber.
    Used to claim loss below 0.3 dB/m and high conversion efficiency; no measured transmission spectrum is shown in the paper.
  • domain assumption GMNA amplification produces a broadband spectrum with near-linear chirp compressible to sub-40 fs with a grating pair.
    Relies on references [23-27]; the paper measures the 38 fs compressed pulse but assumes the GMNA mechanism is fully described by prior work.
  • domain assumption The SHG-FROG retrieval with 0.8% error accurately reconstructs the pulse temporal profile and energy fraction in the main peak.
    The 13 fs duration and 2.2 MW peak power rest on this retrieval; no independent measurement method is provided.
  • domain assumption The RDW is close to transform-limited at the generation point and only positive dispersion after the fiber broadens it, so chirped mirrors can compress it.
    Assumed to justify the compression scheme; based on reference [36] rather than a direct measurement at the generation point.

how reviews work

0 comments
Cite this review

Pith. "Pith review of Tunable megawatt-scale sub-20 fs visible pulses from a fiber laser source." pith.science (2026). https://pith.science/paper/2SIN5YQY

@misc{pith2026250201322,
  author       = {Pith},
  title        = {Pith review of: Tunable megawatt-scale sub-20 fs visible pulses from a fiber laser source},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/2SIN5YQY}},
  note         = {Machine review of arXiv:2502.01322}
}
read the original abstract

Ultrafast laser pulses that are both tunable in wavelength and very short in duration are essential tools in fields ranging from biomedical imaging to ultrafast spectroscopy. While resonant dispersive-wave emission in gas-filled hollow-core fibers is a powerful technique for generating such pulses, it has traditionally required complex and expensive pump laser systems. In this work, we present a more compact and accessible alternative that combines gain-managed nonlinear amplification with resonant dispersive-wave emission. Our system produces sub-20 femtosecond pulses tunable from 400 nm to beyond 700 nm, with energies up to 39 nJ and peak powers exceeding 2 MW, operating at a 4.8 MHz repetition rate. This compact and efficient laser source opens new avenues for deploying resonant dispersive-wave-based technologies for broader scientific and industrial applications.

Figures

Figures reproduced from arXiv: 2502.01322 by the authors.

Figure 1
Figure 1. Experimental setup. LD: laser diode; WDM; wavelength division multiplexer; BBC: birefringent beam combiner; FR: Faraday ro￾tator; λ/2, λ/4: waveplates; PBC: polarizing beam cube; GP: grating pair; HRM: high reflection mirror; PD: photodiode; RFD: radio fre￾quency driver; ISO: isolator; FC: fiber collimator; FC-AOM: fiber-coupled acousto-optic modulator; RM: roof mirror; BPF: bandpass filter; DM: dichroic mirror. A s… view at source ↗
Figure 2
Figure 2. (a) The evolution of GMNA output spectrum as the output pulse energy increases; the inset colorbar indicates the corresponding output pulse energy (nJ). (b) Retrieved temporal profile of the com￾pressed GMNA at the maximum output energy. The dashed line in (a) shows the corresponding retrieved spectrum. the fiber, resulting in a broadband pulse with near-perfect monotonic chirp and a few-ps pulse duration, which can… view at source ↗
Figure 4
Figure 4. (a) The measured and (b) the retrieved FROG traces of the RDW pulse generated at 40 bar. (c) The measured and FROG￾retrieved spectrum of the RDW. (d) The retrieved temporal profile of the pulse. The inset in (d) shows the near-field beam profile of the RDW. and long-pass filter. The RDW energy peaks at around 540 nm with 39 nJ, resulting in a conversion efficiency of approximately 13% from the coupled energy. This h… view at source ↗

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

40 extracted references · 39 canonical work pages

  1. [1]

    W. Denk, J. H. Strickler, and W. W. Webb, Science248, 73 (1990)

    1990

  2. [2]

    Maiuri, M

    M. Maiuri, M. Garavelli, and G. Cerullo, J. Am. Chem. Soc.142, 3 (2020). PMID: 31800225

    work page 2020

  3. [3]

    Kotsina, C

    N. Kotsina, C. Brahms, S. Jackson,et al., Chem. Sci.13, 9586 (2022)

    work page 2022

  4. [4]

    R. Ell, U. Morgner, F . X. Kärtner,et al., Opt. Lett.26, 373 (2001)

    work page 2001

  5. [5]

    Cerullo and S

    G. Cerullo and S. De Silvestri, Rev. Sci. Instruments74, 1 (2003)

    work page 2003

  6. [6]

    Deckert, A

    T. Deckert, A. Vanderhaegen, and D. Brida, Opt. Lett.48, 4496 (2023)

    work page 2023

  7. [7]

    Mevert, Y

    R. Mevert, Y . Binhammer, C. M. Dietrich,et al., Photon. Res.9, 1715 (2021)

    work page 2021

  8. [8]

    Tu and S

    H. Tu and S. A. Boppart, Laser & Photonics Rev.7, 628 (2013)

    work page 2013

Show all 40 references
  1. [9]

    N. Y . Joly, J. Nold, W. Chang,et al., Phys. Rev. Lett.106, 203901 (2011)

    2011

  2. [10]

    K. F . Mak, J. C. Travers, P . Hölzer,et al., Opt. Express21, 10942 (2013)

    2013

  3. [11]

    Belli, A

    F . Belli, A. Abdolvand, W. Chang,et al., Optica2, 292 (2015)

    2015

  4. [12]

    K. F . Mak, M. Seidel, O. Pronin,et al., Opt. Lett.40, 1238 (2015)

    2015

  5. [13]

    Köttig, F

    F . Köttig, F . Tani, C. M. Biersach,et al., Optica4, 1272 (2017)

    2017

  6. [14]

    J. C. Travers, T. F . Grigorova, C. Brahms, and F . Belli, Nat. Photonics 13, 547 (2019)

    2019

  7. [15]

    Erkintalo, Y

    M. Erkintalo, Y . Q. Xu, S. G. Murdoch,et al., Phys. Rev. Lett.109, 223904 (2012)

    2012

  8. [16]

    Brahms, D

    C. Brahms, D. R. Austin, F . Tani,et al., Opt. Lett.44, 731 (2019)

    2019

  9. [17]

    Reduzzi, M

    M. Reduzzi, M. Pini, L. Mai,et al., Opt. Express31, 26854 (2023)

    2023

  10. [18]

    J. M. Dudley, G. Genty, and S. Coen, Rev. Mod. Phys.78, 1135 (2006)

    2006

  11. [19]

    Sabbah, K

    M. Sabbah, K. Harrington, L. R. Murphy,et al., Opt. Lett.49, 3090 (2024)

    2024

  12. [20]

    W. Liu, R. Liao, J. Zhao,et al., Optica6, 194 (2019)

    2019

  13. [21]

    Repgen, D

    P . Repgen, D. Wandt, U. Morgner,et al., Opt. Lett.44, 5973 (2019)

    2019

  14. [22]

    Sidorenko and F

    P . Sidorenko and F . Wise, Opt. Lett.45, 4084 (2020)

    2020

  15. [23]

    Sidorenko, W

    P . Sidorenko, W. Fu, and F . Wise, Optica6, 1328 (2019)

    2019

  16. [24]

    M. E. Fermann, V. I. Kruglov, B. C. Thomsen,et al., Phys. Rev. Lett.84, 6010 (2000)

    2000

  17. [25]

    Tomaszewska-Rolla, R

    D. Tomaszewska-Rolla, R. Lindberg, V. Pasiskevicius,et al., Sci. Re- ports12, 404 (2022)

    2022

  18. [26]

    B. Ren, C. Li, T. Wang,et al., Opt. & Laser Technol.160, 109081 (2023)

    2023

  19. [27]

    Boulanger, M

    V. Boulanger, M. Olivier, F . Trépanier,et al., Opt. Lett.48, 2700 (2023)

    2023

  20. [28]

    Jiang, Y

    T. Jiang, Y . Cui, P . Lu,et al., IEEE Photonics Technol. Lett.28, 1786 (2016)

    2016

  21. [29]

    A. S. Mayer, W. Grosinger, J. Fellinger,et al., Opt. Express28, 18946 (2020)

    2020

  22. [30]

    Russell, Science299, 358 (2003)

    P . Russell, Science299, 358 (2003)

    2003

  23. [31]

    Poletti, M

    F . Poletti, M. N. Petrovich, and D. J. Richardson, Nanophotonics2, 315 (2013)

    2013

  24. [32]

    N. M. Litchinitser, A. K. Abeeluck, C. Headley, and B. J. Eggleton, Opt. Lett.27, 1592 (2002)

    2002

  25. [33]

    Yu and J

    F . Yu and J. Knight, IEEE J. Sel. Top. Quantum Electron.22, 1 (2016)

    2016

  26. [34]

    F . Tani, F . Köttig, D. Novoa,et al., Photon. Res.6, 84 (2018)

    2018

  27. [35]

    Biancalana, D

    F . Biancalana, D. V. Skryabin, and A. V. Yulin, Phys. Rev. E70, 016615 (2004)

    2004

  28. [36]

    Ermolov, H

    A. Ermolov, H. Valtna-Lukner, J. Travers, and P . S. Russell, Opt. Lett. 41, 5535 (2016)

    2016

  29. [37]

    Erkintalo, C

    M. Erkintalo, C. Aguergaray, A. Runge, and N. G. R. Broderick, Opt. Express20, 22669 (2012)

    2012

  30. [38]

    Tuneable megawatt-scale sub-15 fs visible pulses via dispersive wave emission pumped by a gain managed fiber amplifier,

    M. Sabbah, R. Mears, L. Murphy,et al., “Tuneable megawatt-scale sub-15 fs visible pulses via dispersive wave emission pumped by a gain managed fiber amplifier,” inLaser Congress 2024 (ASSL, LAC, LS&C),(Optica Publishing Group, 2024), p. AW6A.4

    2024

  31. [39]

    F . Tani, J. Lampen, M. Butryn,et al., Phys. Rev. Appl.18, 064069 (2022)

    2022

  32. [40]

    Y .-H. Chen, P . Sidorenko, E. Antonio-Lopez,et al., Opt. Lett.47, 285 (2022)

    2022

Pith tools

Reviewed August 9, 2026 · model on record in the stance chip above.