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arxiv: 2603.26470 · v1 · submitted 2026-03-27 · ⚛️ physics.optics · cond-mat.mtrl-sci· physics.app-ph

Efficient Picosecond-Laser Lift-Off of Copper Oxide from Copper: Modelling and Experiment

Andrius \v{Z}emaitis , Paulius Ge\v{c}ys , Mindaugas Gedvilas This is my paper

Pith reviewed 2026-05-14 22:19 UTC · model grok-4.3

classification ⚛️ physics.optics cond-mat.mtrl-sciphysics.app-ph
keywords laser-induced lift-offGaussian beamsfluence optimizationpicosecond lasercopper oxide delaminationthreshold modelmicrofabrication
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The pith

Maximum lifted-off area with a Gaussian laser beam occurs at peak fluence of e times the threshold fluence

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

The paper develops an analytical model for the area of material lifted off by a Gaussian laser pulse. It shows that this area reaches its maximum when the peak fluence is e times the threshold fluence, unlike the e squared factor optimal for maximizing ablated volume in ablation processes. Closed-form expressions for the optimal beam radius and focus position are provided and confirmed by experiments on picosecond laser removal of copper oxide from copper. This optimization criterion enables more efficient use of laser energy in lift-off applications such as microfabrication and surface functionalization.

Core claim

In analogy to efficient laser ablation, a theoretical framework is developed for efficient laser lift-off driven by Gaussian beams. The lift-off area is analytically described as a function of peak fluence, beam radius, and focus position. The maximum lifted-off area is achieved at a peak fluence of e F_th. Closed-form expressions for the optimal beam radius, maximal lift-off area, and optimal focus position are derived and validated experimentally for picosecond laser lift-off of copper oxide from copper.

What carries the argument

The analytical lift-off area function derived by integrating over the region of the Gaussian fluence profile exceeding the threshold fluence, parameterized by peak fluence, beam radius, and focus position.

If this is right

  • Optimal peak fluence for lift-off is e F_th, lower than e^2 F_th for ablation.
  • Direct calculation of optimal beam radius and focus position without iteration.
  • Model predictions match experimental lift-off areas for copper oxide.
  • Highlights that lift-off processes are area-based rather than volume-based.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same ratio symmetry principle could apply to other laser processes with threshold behavior.
  • In industrial settings, this could reduce required laser power for coating removal tasks.
  • Future work might incorporate thermal effects to extend applicability to different materials.

Load-bearing premise

The model assumes a sharp fluence threshold for lift-off with no thermal diffusion, incubation effects, or material-specific dynamics beyond the binary on/off region.

What would settle it

An experiment varying peak fluence around e F_th while measuring the lifted-off area for a fixed beam setup; if the peak area is not at e F_th, the model is falsified.

read the original abstract

Laser-induced lift-off of functional surface layers is a key process in micro- and nano-fabrication; however, optimization criteria for maximizing the lifted-off area remain insufficiently defined. In analogy to the well-established theory of efficient laser ablation, where the maximum ablated volume per pulse is achieved at a peak fluence of F_0^{\mathrm{opt}} = e^{2} F_{\mathrm{th}}, we develop a theoretical framework for efficient laser lift-off driven by Gaussian beams. By analytically describing the lift-off area as a function of peak fluence, beam radius, and focus position, we demonstrate that the maximum lifted-off area is achieved at a substantially lower optimal fluence, namely F_0^{\mathrm{opt}} = e^{1} F_{\mathrm{th}}. Closed-form expressions for the optimal beam radius, maximal lift-off area, and optimal focus position are derived and validated by numerical modeling. The theory is applied to picosecond laser lift-off of copper oxide from copper, showing excellent agreement between experimental observations and model predictions. The results reveal fundamental differences between ablation- and lift-off-dominated material removal and provide practical guidelines for maximizing process efficiency in laser-assisted delamination, selective coating removal, and surface functionalization.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

0 major / 2 minor

Summary. The manuscript develops an analytical model for the area lifted off by a Gaussian laser beam, deriving closed-form expressions showing that the maximum lifted-off area occurs at peak fluence F_0^opt = e F_th (in contrast to the e^2 F_th rule for ablation). The model is validated by numerical integration and by quantitative agreement with picosecond-laser experiments on copper-oxide lift-off from copper, yielding practical expressions for optimal beam radius, focus position, and maximal area.

Significance. If the central result holds, the work supplies a simple, single-parameter optimization rule that is directly usable for process design in laser delamination and selective coating removal. The closed-form derivation, its reduction to a single fitted threshold F_th, and the reported numerical-experimental agreement constitute clear strengths that distinguish lift-off from ablation physics.

minor comments (2)
  1. [Theoretical Framework] The model rests on the binary threshold assumption (no thermal diffusion, incubation, or material-specific dynamics). While this yields the clean analytic result, a brief discussion of the fluence range over which the assumption remains valid would help readers assess applicability beyond the reported CuO/Cu case.
  2. [Experimental Validation] Full tables of fitted parameters, experimental uncertainties, and goodness-of-fit metrics for the lift-off area data would make the validation section more transparent; these details are referenced but not fully tabulated in the current manuscript.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for the positive assessment of our manuscript and for recommending minor revision. The referee's summary accurately reflects the core contribution: an analytical Gaussian-beam lift-off model that yields a closed-form optimum at F_0^opt = e F_th, together with validated expressions for optimal radius, focus position, and maximum area. We appreciate the recognition that this result is distinct from the e^2 F_th ablation rule and directly usable for process design.

Circularity Check

0 steps flagged

No significant circularity

full rationale

The central result F_0^opt = e F_th is obtained by maximizing the closed-form lift-off area A = π w² ln(F0/F_th) (or equivalent Gaussian form) subject to fixed pulse energy E ∝ F0 w². Differentiating yields the stationary point at ln(F0/F_th)=1 with no fitted parameters or self-referential definitions involved. The analogy to the e² ablation case is cited as external precedent but the lift-off derivation is performed independently from the stated assumptions. No self-citation chains, smuggled ansatzes, or renaming of known results appear in the load-bearing steps; the model is self-contained against its explicit inputs and externally validated by experiment.

Axiom & Free-Parameter Ledger

1 free parameters · 2 axioms · 0 invented entities

The framework rests on the standard Gaussian intensity profile for the beam and the domain assumption of a sharp fluence threshold for lift-off; no new entities are postulated and the only free parameter is the experimentally determined threshold fluence.

free parameters (1)
  • F_th
    Threshold fluence below which no lift-off occurs; determined from experiment or prior knowledge and used to normalize the optimal fluence.
axioms (2)
  • standard math Laser beam intensity follows a Gaussian spatial profile.
    Invoked to express fluence as a function of radial distance and focus position.
  • domain assumption Lift-off occurs wherever local fluence exceeds a sharp threshold F_th.
    Direct analogy to the ablation threshold model; stated in the theoretical framework section.

pith-pipeline@v0.9.0 · 5537 in / 1433 out tokens · 33690 ms · 2026-05-14T22:19:37.017965+00:00 · methodology

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Works this paper leans on

31 extracted references · 31 canonical work pages

  1. [1]

    Ultrafast Laser Processing of Materials: From Science to Industry

    Malinauskas, M.; Žukauskas, A.; Hasegawa, S.; Hayasaki, Y.; Mizeikis, V.; Buividas, R.; Juodkazis, S. Ultrafast Laser Processing of Materials: From Science to Industry. Light Sci. Appl. 2016, 5, e16133–e16133, doi:10.1038/lsa.2016.133

    work page doi:10.1038/lsa.2016.133 2016

  2. [2]

    A Review of Laser Materials Processing Paradigms

    Tumkur, T .U.; Li, R.; Korakis, V.; Lantzsch, T .; Willenborg, E.; Vedder, C.; Laurence, T .A.; Beach, R.J.; Häfner, C.; Grigoropoulos, C.P .; et al. A Review of Laser Materials Processing Paradigms. MRS Bull. 2025, 50, 1519–1538, doi:10.1557/s43577-025-01021-7

    work page doi:10.1557/s43577-025-01021-7 2025

  3. [3]

    A Review of Ultrafast Laser Micro/Nano Fabrication: Material Processing, Surface/Interface Controlling, and Devices Fabrication

    Guo, H.; Xie, J.; He, G.; Zhu, D.; Qiao, M.; Yan, J.; Yu, J.; Li, J.; Zhao, Y.; Luo, M.; et al. A Review of Ultrafast Laser Micro/Nano Fabrication: Material Processing, Surface/Interface Controlling, and Devices Fabrication. Nano Res. 2024, 17, 6212–6230, doi:10.1007/s12274- 024-6644-z

    work page doi:10.1007/s12274- 2024

  4. [4]

    Femtosecond Laser Micro/Nano Processing: From Fundamental to Applications

    Gao, L.; Zhang, Q.; Gu, M. Femtosecond Laser Micro/Nano Processing: From Fundamental to Applications. International Journal of Extreme Manufacturing 2025, 7, 022010, doi:10.1088/2631-7990/ad943e

    work page doi:10.1088/2631-7990/ad943e 2025

  5. [5]

    Femtosecond, Picosecond and Nanosecond Laser Ablation of Solids

    Chichkov, B.N.; Momma, C.; Nolte, S.; Alvensleben, F.; Tünnermann, A. Femtosecond, Picosecond and Nanosecond Laser Ablation of Solids. Appl. Phys. A Mater. Sci. Process. 1996, 63, 109–115, doi:10.1007/BF01567637

    work page doi:10.1007/bf01567637 1996

  6. [6]

    Mechanisms of Ultrafast GHz Burst Fs Laser Ablation

    Park, M.; Gu, Y.; Mao, X.; Grigoropoulos, C.P .; Zorba, V. Mechanisms of Ultrafast GHz Burst Fs Laser Ablation. Sci. Adv. 2023, 9, eadf639, doi:10.1126/sciadv.adf6397

    work page doi:10.1126/sciadv.adf6397 2023

  7. [7]

    ¨O.: Ablation-cooled material removal with ultrafast bursts of pulses

    Kerse, C.; Kalaycıoğlu, H.; Elahi, P .; Çetin, B.; Kesim, D.K.; Akçaalan, Ö.; Yavaş, S.; Aşık, M.D.; Öktem, B.; Hoogland, H.; et al. Ablation-Cooled Material Removal with Ultrafast Bursts of Pulses. Nature 2016, 537, 84–88, doi:10.1038/nature18619

    work page doi:10.1038/nature18619 2016

  8. [8]

    Recent Advances in Applications of Ultrafast Lasers

    Niu, S.; Wang, W.; Liu, P .; Zhang, Y.; Zhao, X.; Li, J.; Xiao, M.; Wang, Y.; Li, J.; Shao, X. Recent Advances in Applications of Ultrafast Lasers. Photonics 2024, 11, 857, doi:10.3390/photonics11090857. 17

    work page doi:10.3390/photonics11090857 2024

  9. [9]

    Laser Applications in Surface Treatment: A Comprehensive Review

    Ambhore, N.; Manikanta, J.E.; Gurajala, N.K.; Nikhare, C. Laser Applications in Surface Treatment: A Comprehensive Review. Laser Phys. 2025, 35, 106101, doi:10.1088/1555- 6611/ae0df3

    work page doi:10.1088/1555- 2025

  10. [10]

    A Review of Research on Material Removal Mechanisms for Laser-Assisted Machining of Difficult-to-Machine Materials

    Xiao, G.; Wang, J.; Zhu, S.; He, Y.; Liu, Z.; Huang, Y. A Review of Research on Material Removal Mechanisms for Laser-Assisted Machining of Difficult-to-Machine Materials. Surface Science and Technology 2023, 1, 8, doi:10.1007/s44251-023-00007-4

    work page doi:10.1007/s44251-023-00007-4 2023

  11. [11]

    Mechanisms of Laser Ablation in Liquids and Their Impact on the Efficiency of Nanoparticle Generation

    Spellauge, M.; Redka, D.; Podhrazsky, A.; Eckmann, K.; Eulenkamp, C.; Koepp, O.; Doñate‐ Buendia, C.; Gökce, B.; Barcikowski, S.; Huber, H.P . Mechanisms of Laser Ablation in Liquids and Their Impact on the Efficiency of Nanoparticle Generation. Laser Photon. Rev. 2025, 0, e01348, doi:10.1002/lpor.202501348

    work page doi:10.1002/lpor.202501348 2025

  12. [12]

    The atomistic perspective of nanoscale laser ablation

    Ivanov, D.S.; Terekhin, P .N.; Kudryashov, S.I.; Klimentov, S.M.; Kabashin, A. V.; Garcia, M.E.; Rethfeld, B.; Zavestovskaya, I.N. The Atomistic Perspective of Nanoscale Laser Ablation. In Ultrafast Laser Nanostructuring; Stoian, R.,, Bonse, J., Eds.; Springer, Cham.: doi:10.1007/978-3-031-14752-4_2, 2023; Vol. 239, pp. 65–137

    work page doi:10.1007/978-3-031-14752-4_2 2023

  13. [13]

    Deterministic Processing of Alumina with Ultrashort Laser Pulses

    Furmanski, J.; Rubenchik, A.M.; Shirk, M.D.; Stuart, B.C. Deterministic Processing of Alumina with Ultrashort Laser Pulses. J Appl Phys 2007, 102, 073112, doi:10.1063/1.2794376

    work page doi:10.1063/1.2794376 2007

  14. [14]

    Use of High Repetition Rate and High Power Lasers in Microfabrication: How to Keep the Efficiency High? J Laser Micro Nanoen 2009, 4, 186–191, doi:10.2961/jlmn.2009.03.0008

    Račiukaitis, G.; Gečys, P .; Brikas, M.; Voisiat, B.; Gedvilas, M. Use of High Repetition Rate and High Power Lasers in Microfabrication: How to Keep the Efficiency High? J Laser Micro Nanoen 2009, 4, 186–191, doi:10.2961/jlmn.2009.03.0008

    work page doi:10.2961/jlmn.2009.03.0008 2009

  15. [15]

    Processing of Metals and Dielectric Materials with Ps-Laserpulses: Results, Strategies, Limitations and Needs

    Neuenschwander, B.; Bucher, G.F.; Nussbaum, C.; Joss, B.; Muralt, M.; Hunziker, U.W.; Schuetz, P . Processing of Metals and Dielectric Materials with Ps-Laserpulses: Results, Strategies, Limitations and Needs. Proc. SPIE 2010, 7584, 75840R, doi:10.1117/12.846521

    work page doi:10.1117/12.846521 2010

  16. [16]

    Efficient Ablation, Further GHz Burst Polishing, and Surface Texturing by Ultrafast Laser

    Žemaitis, A.; Gečys, P .; Gedvilas, M. Efficient Ablation, Further GHz Burst Polishing, and Surface Texturing by Ultrafast Laser. Adv. Eng. Mater. 2024, 26, 2302262, doi:10.1002/adem.202302262

    work page doi:10.1002/adem.202302262 2024

  17. [17]

    Efficient Picosecond Laser Ablation of Copper Cylinders

    Gaidys, M.; Žemaitis, A.; Gečys, P .; Gedvilas, M. Efficient Picosecond Laser Ablation of Copper Cylinders. Appl. Surf. Sci. 2019, 483, 962–966, doi:10.1016/j.apsusc.2019.04.002

    work page doi:10.1016/j.apsusc.2019.04.002 2019

  18. [18]

    Bi-Stability in Femtosecond Laser Ablation by MHz Bursts

    Žemaitis, A.; Gaidys, M.; Gečys, P .; Gedvilas, M. Bi-Stability in Femtosecond Laser Ablation by MHz Bursts. Sci. Rep. 2024, 14, 5614, doi:10.1038/s41598-024-54928-7. 18

    work page doi:10.1038/s41598-024-54928-7 2024

  19. [19]

    The Ultrafast Burst Laser Ablation of Metals: Speed and Quality Come Together

    Žemaitis, A.; Gudauskytė, U.; Steponavičiūtė, S.; Gečys, P .; Gedvilas, M. The Ultrafast Burst Laser Ablation of Metals: Speed and Quality Come Together. Opt. Laser Technol. 2025, 180, 111458, doi:10.1016/j.optlastec.2024.111458

    work page doi:10.1016/j.optlastec.2024.111458 2025

  20. [20]

    Influence of Nonlinear and Saturable Absorption on Laser Lift-off Threshold of an Oxide/Metal Structure

    Žemaitis, A.; Gaidys, M.; Gečys, P .; Gedvilas, M. Influence of Nonlinear and Saturable Absorption on Laser Lift-off Threshold of an Oxide/Metal Structure. Opt. Lett. 2020, 45, 6166, doi:10.1364/OL.404760

    work page doi:10.1364/ol.404760 2020

  21. [21]

    Picosecond Laser Lift-off Method for Fracture and Debonding of Copper Oxide Layer Grown on Copper Substrate

    Zhu, H.; Zhang, H.; Ni, X.; Shen, Z.; Lu, J. Picosecond Laser Lift-off Method for Fracture and Debonding of Copper Oxide Layer Grown on Copper Substrate. J. Laser Appl. 2019, 31, 042015, doi:10.2351/1.5121339

    work page doi:10.2351/1.5121339 2019

  22. [22]

    Ultrafast Laser Ablation and Modification of Thin Metal Film for Quasi-1D Array Formation

    Vilkevičius, K.; Čepaitis, K.; Selskis, A.; Stankevičius, E. Ultrafast Laser Ablation and Modification of Thin Metal Film for Quasi-1D Array Formation. Opt. Laser Technol. 2025, 183, 112330, doi:10.1016/j.optlastec.2024.112330

    work page doi:10.1016/j.optlastec.2024.112330 2025

  23. [23]

    Ultrashort Pulsed Laser Induced Material Lift-off Processing of CZTSe Thin-Film Solar Cells

    Gecys, P .; Markauskas, E.; Gedvilas, M.; Raciukaitis, G.; Repins, I.; Beall, C. Ultrashort Pulsed Laser Induced Material Lift-off Processing of CZTSe Thin-Film Solar Cells. Solar Energy 2014, 102, 82–90, doi:10.1016/j.solener.2014.01.013

    work page doi:10.1016/j.solener.2014.01.013 2014

  24. [24]

    CIGS Thin-Film Solar Module Processing: Case of High-Speed Laser Scribing

    Gečys, P .; Markauskas, E.; Nishiwaki, S.; Buecheler, S.; De Loor, R.; Burn, A.; Romano, V.; Račiukaitis, G. CIGS Thin-Film Solar Module Processing: Case of High-Speed Laser Scribing. Sci. Rep. 2017, 7, 40502, doi:10.1038/srep40502

    work page doi:10.1038/srep40502 2017

  25. [25]

    Graphene- Enabled Laser Lift-off for Ultrathin Displays

    Kang, S.; Chang, J.; Lim, J.; Kim, D.J.; Kim, T .-S.; Choi, K.C.; Lee, J.H.; Kim, S. Graphene- Enabled Laser Lift-off for Ultrathin Displays. Nat. Commun. 2024, 15, 8288, doi:10.1038/s41467-024-52661-3

    work page doi:10.1038/s41467-024-52661-3 2024

  26. [26]

    Photonic Lift-off Process to Fabricate Ultrathin Flexible Solar Cells

    Liu, W.; Turkani, V.S.; Akhavan, V.; Korgel, B.A. Photonic Lift-off Process to Fabricate Ultrathin Flexible Solar Cells. ACS Appl. Mater. Interfaces 2021, 13, 44549–44555, doi:10.1021/acsami.1c12382

    work page doi:10.1021/acsami.1c12382 2021

  27. [27]

    Laser Lift-off Mechanism and Optical-Electric Characteristics of Red Micro-LED Devices

    Tian, W.; Wu, Y.; Xiao, J.; Wang, P .; Li, J. Laser Lift-off Mechanism and Optical-Electric Characteristics of Red Micro-LED Devices. Opt. Express 2023, 31, 7887, doi:10.1364/OE.475270

    work page doi:10.1364/oe.475270 2023

  28. [28]

    Thermoelastic Modeling of Microbump and Nanojet Formation on Nanosize Gold Films under Femtosecond Laser Irradiation

    Meshcheryakov, Y.P .; Bulgakova, N.M. Thermoelastic Modeling of Microbump and Nanojet Formation on Nanosize Gold Films under Femtosecond Laser Irradiation. Applied Physics A 2006, 82, 363–368, doi:10.1007/s00339-005-3319-9. 19

    work page doi:10.1007/s00339-005-3319-9 2006

  29. [29]

    Advanced Laser Scanning for Highly-Efficient Ablation and Ultrafast Surface Structuring: Experiment and Model

    Žemaitis, A.; Gaidys, M.; Brikas, M.; Gečys, P .; Račiukaitis, G.; Gedvilas, M. Advanced Laser Scanning for Highly-Efficient Ablation and Ultrafast Surface Structuring: Experiment and Model. Sci. Rep. 2018, 8, 17376, doi:10.1038/s41598-018-35604-z

    work page doi:10.1038/s41598-018-35604-z 2018

  30. [30]

    Simple technique for measurements of pulsed Gaussian-beam spot sizes

    Liu, J.M. Simple Technique for Measurements of Pulsed Gaussian-Beam Spot Sizes. Opt. Lett. 1982, 7, 196, doi:10.1364/OL.7.000196

    work page doi:10.1364/ol.7.000196 1982

  31. [31]

    Highly-Efficient Laser Ablation of Copper by Bursts of Ultrashort Tuneable (Fs-Ps) Pulses

    Žemaitis, A.; Gečys, P .; Barkauskas, M.; Račiukaitis, G.; Gedvilas, M. Highly-Efficient Laser Ablation of Copper by Bursts of Ultrashort Tuneable (Fs-Ps) Pulses. Sci. Rep. 2019, 9, 12280, doi:10.1038/s41598-019-48779-w

    work page doi:10.1038/s41598-019-48779-w 2019