title: Ablation-cooled material removal with ultrafast bursts of pulses.
abstract: The use of femtosecond laser pulses allows precise and thermal-damage-free removal of material (ablation) with wide-ranging scientific, medical and industrial applications. However, its potential is limited by the low speeds at which material can be removed and the complexity of the associated laser technology. The complexity of the laser design arises from the need to overcome the high pulse energy threshold for efficient ablation. However, the use of more powerful lasers to increase the ablation rate results in unwanted effects such as shielding, saturation and collateral damage from heat accumulation at higher laser powers. Here we circumvent this limitation by exploiting ablation cooling, in analogy to a technique routinely used in aerospace engineering. We apply ultrafast successions (bursts) of laser pulses to ablate the target material before the residual heat deposited by previous pulses diffuses away from the processing region. Proof-of-principle experiments on various substrates demonstrate that extremely high repetition rates, which make ablation cooling possible, reduce the laser pulse energies needed for ablation and increase the efficiency of the removal process by an order of magnitude over previously used laser parameters. We also demonstrate the removal of brain tissue at two cubic millimetres per minute and dentine at three cubic millimetres per minute without any thermal damage to the bulk.
authors.affiliation: Department of Electrical and Electronics Engineering, Bilkent University, Ankara 06800, Turkey.
authors.forename: Can
authors.initials: C
authors.lastname: Kerse
authors.affiliation: Department of Physics, Bilkent University, Ankara 06800, Turkey.
authors.forename: Hamit
authors.initials: H
authors.lastname: Kalaycıoğlu
authors.affiliation: Department of Physics, Bilkent University, Ankara 06800, Turkey.
authors.forename: Parviz
authors.initials: P
authors.lastname: Elahi
authors.affiliation: Department of Mechanical Engineering, Bilkent University, Ankara 06800, Turkey.
authors.forename: Barbaros
authors.initials: B
authors.lastname: Çetin
authors.affiliation: Department of Electrical and Electronics Engineering, Bilkent University, Ankara 06800, Turkey.
authors.forename: Denizhan K
authors.initials: DK
authors.lastname: Kesim
authors.affiliation: Department of Electrical and Electronics Engineering, Bilkent University, Ankara 06800, Turkey.
authors.forename: Önder
authors.initials: Ö
authors.lastname: Akçaalan
authors.affiliation: FiberLAST, Inc., Ankara 06531, Turkey.
authors.forename: Seydi
authors.initials: S
authors.lastname: Yavaş
authors.affiliation: Nanotechnology and Nanomedicine Department, Hacettepe University, Ankara 06800, Turkey.
authors.forename: Mehmet D
authors.initials: MD
authors.lastname: Aşık
authors.affiliation: ASELSAN, Ankara 06150, Turkey.
authors.forename: Bülent
authors.initials: B
authors.lastname: Öktem
authors.affiliation: Menlo Systems GmbH, Am Kloperspitz 19a, Martinsried 82152, Germany.|Lehrstuhl für Laserphysik, Department Physik, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen 91058, Germany.
authors.forename: Heinar
authors.initials: H
authors.lastname: Hoogland
authors.affiliation: Menlo Systems GmbH, Am Kloperspitz 19a, Martinsried 82152, Germany.
authors.forename: Ronald
authors.initials: R
authors.lastname: Holzwarth
authors.affiliation: Department of Electrical and Electronics Engineering, Bilkent University, Ankara 06800, Turkey.|Department of Physics, Bilkent University, Ankara 06800, Turkey.
authors.forename: Fatih Ömer
authors.initials: FÖ
authors.lastname: Ilday
mesh_terms: D000818:Animals; D001921:Brain / Q000601:surgery; D002417:Cattle; D003080:Cold Temperature; D003315:Cornea / Q000601:surgery; D003804:Dentin / Q000601:surgery; D006358:Hot Temperature; D006801:Humans; D053685:Laser Therapy / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods*; D007834:Lasers / Q000009:adverse effects*; D051381:Rats; D013997:Time Factors