Transition and self-healing process between chaotic and self-organized patterns observed during femtosecond laser writing

Groothoff, Nathaniel; Hongler, Max-Olivier; Kazansky, Peter G.; Bellouard, Yves

doi:10.1364/oe.23.016993

Cited by 7 publications

(3 citation statements)

References 24 publications

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“…It is worth noting that the observed switching from the damage-like to nanograting modification is different from the transition and self-healing process of nanogratings that is dependent on the randomness of crack initiation in glass 42 . This transition can revert back from one state to another simply by continuing the writing process, while the transition observed in our experiment is irreversible.…”

Section: Discussionmentioning

confidence: 86%

Direct Writing with Tilted-Front Femtosecond Pulses

Patel

Svirko

Durfee

et al. 2017

Sci Rep

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Shaping light fields in both space and time provides new degrees of freedom to manipulate light-matter interaction on the ultrafast timescale. Through this exploitation of the light field, a greater appreciation of spatio-temporal couplings in focusing has been gained, shedding light on previously unexplored parameters of the femtosecond light pulse, including pulse front tilt and wavefront rotation. Here, we directly investigate the effect of major spatio-temporal couplings on light-matter interaction and reveal unambiguously that in transparent media, pulse front tilt gives rise to the directional asymmetry of the ultrafast laser writing. We demonstrate that the laser pulse with a tilted intensity front deposits energy more efficiently when writing along the tilt than when writing against, producing either an isotropic damage-like or a birefringent nanograting structure. The directional asymmetry in the ultrafast laser writing is qualitatively described in terms of the interaction of a void trapped within the focal volume by the gradient force from the tilted intensity front and the thermocapillary force caused by the gradient of temperature. The observed instantaneous transition from the damage-like to nanograting modification after a finite writing length in a transparent dielectric is phenomenologically described in terms of the first-order phase transition.

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Section: Discussionmentioning

confidence: 86%

Direct Writing with Tilted-Front Femtosecond Pulses

Patel

Svirko

Durfee

et al. 2017

Sci Rep

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“…A buried dynamic near-critical electron-hole plasma, supporting interfacial plasmon-polaritons during the bulk refractive-index difference (RID) laser inscription, could be produced either in pre-filamentation (linear/geometrical focusing) [ 11 ] or in filamentation (non-linear self-focusing) regimes [ 12 ]. Importantly, nano/microscale damage morphologies—nano- [ 1 , 3 ] and microcavities [ 13 , 14 ], microtracks [ 12 ], etc., accompanying the pre- or filamentation regimes, could be managed by laser pulse wavelength, energy, width and focusing conditions via filamentation and laser-deposited energy density control [ 6 , 15 , 16 ] in order to reduce scattering losses and boost the related functional modalities (e.g., RID amplitude and thickness T ). However, the current understanding of the role of filamentation and basic physical processes underlying ultrashort-pulse laser inscription of birefringent nanolattices in bulk dielectrics is still challenging and controversial [ 1 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

Multi-Parametric Birefringence Control in Ultrashort-Pulse Laser-Inscribed Nanolattices in Fluorite

et al. 2023

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An ultrashort-pulse laser inscription of embedded birefringent microelements was performed inside bulk fluorite in pre-filamentation (geometrical focusing) and filamentation regimes as a function of laser wavelength, pulsewidth and energy. The resulting elements composed of anisotropic nanolattices were characterized by retardance (Ret) and thickness (T) quantities, using polarimetric and 3D-scanning confocal photoluminescence microscopy, respectively. Both parameters exhibit a monotonous increase versus pulse energy, going over a maximum at 1-ps pulsewidth at 515 nm, but decrease versus laser pulsewidth at 1030 nm. The resulting refractive-index difference (RID) Δn = Ret/T ~ 1 × 10−3 remains almost constant versus pulse energy and slightly decreases at a higher pulsewidth, generally being higher at 515 nm. The birefringent microelements were visualized using scanning electron microscopy and chemically characterized using energy-dispersion X-ray spectroscopy, indicating the increase of calcium and the contrary decrease of fluorine inside them due to the non-ablative inscription character. Dynamic far-field optical diffraction of the inscribing ultrashort laser pulses also demonstrated the accumulative inscription character, depending on the pulse energy and the laser exposure. Our findings revealed the underlying optical and material inscription processes and demonstrated the robust longitudinal homogeneity of the inscribed birefringent microstructures and the facile scalability of their thickness-dependent retardance.

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“…When optimal irradiation parameters are used, the laser-induced modification enhances the local etchability of the silica by up to three orders of magnitude [15,16], allowing the laser-inscribed material to be subsequently removed in a second, chemical etching step. Within the last two decades, collaborative efforts towards better understanding the light-matter interactions [17][18][19] and chemical etching mechanisms [20] and advanced writing techniques [21,22] have established ULAE as a capable manufacturing method for complex glass microcomponents and systems [23,24]. Recently, ULAE has shifted away from using the widely adopted but notoriously hazardous etching agent hydrofluoric acid (HF) to potassium hydroxide (KOH), making the technique much more appealing for industry-level manufacturing.…”

Section: Introductionmentioning

confidence: 99%

A Miniature Fibre-Optic Raman Probe Fabricated by Ultrafast Laser-Assisted Etching

et al. 2020

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Optical biopsy describes a range of medical procedures in which light is used to investigate disease in the body, often in hard-to-reach regions via optical fibres. Optical biopsies can reveal a multitude of diagnostic information to aid therapeutic diagnosis and treatment with higher specificity and shorter delay than traditional surgical techniques. One specific type of optical biopsy relies on Raman spectroscopy to differentiate tissue types at the molecular level and has been used successfully to stage cancer. However, complex micro-optical systems are usually needed at the distal end to optimise the signal-to-noise properties of the Raman signal collected. Manufacturing these devices, particularly in a way suitable for large scale adoption, remains a critical challenge. In this paper, we describe a novel fibre-fed micro-optic system designed for efficient signal delivery and collection during a Raman spectroscopy-based optical biopsy. Crucially, we fabricate the device using a direct-laser-writing technique known as ultrafast laser-assisted etching which is scalable and allows components to be aligned passively. The Raman probe has a sub-millimetre diameter and offers confocal signal collection with 71.3% ± 1.5% collection efficiency over a 0.8 numerical aperture. Proof of concept spectral measurements were performed on mouse intestinal tissue and compared with results obtained using a commercial Raman microscope.

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Transition and self-healing process between chaotic and self-organized patterns observed during femtosecond laser writing

Cited by 7 publications

References 24 publications

Direct Writing with Tilted-Front Femtosecond Pulses

Direct Writing with Tilted-Front Femtosecond Pulses

Multi-Parametric Birefringence Control in Ultrashort-Pulse Laser-Inscribed Nanolattices in Fluorite

A Miniature Fibre-Optic Raman Probe Fabricated by Ultrafast Laser-Assisted Etching

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