NANOFLAM. Projet ANR Blanc 2011 BS Aide allouée: , durée 36+8 mois (fin : Mai 2015) Laboratoire H. Curien

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1 Laboratoire H. Curien Centre de Physique Théorique F. Courvoisier R. Stoian & T. Itina A. Couairon NANOFLAM Projet ANR Blanc 2011 BS Contrôle de la filamentation et de la génération de plasma avec les impulsions non-diffractantes femtoseconde en régime nonlinéaire. Applications à la nano-structuration laser à haut rapport de forme. Aide allouée: , durée 36+8 mois (fin : Mai 2015)

2 Motivations The control of the longitudinal profile of ablation structures during drilling and dicing is a key technological issue. Nanofluidics Nanophotonics Femtosecond laser processing Less precise Simple, single step 3D in transparent materials 3D microelectronics Lithography Precise Complex, multisteps Limited to 2D, aspect ratio <10 Glass & solar panels 2

3 Motivations Femtosecond lasers have enabled significant progresses for precision micro and nanofabrication with ablation accuracy down to ~ nm. 3

4 Problem: energy deposition in matter Weakly focused Gaussian beams yield pulse spatio-temporal distorsions (filamentation, splitting ) Intensity clamping prevents high intensities at focus. Self-focusing Plasma Absorption & Diffraction Sudrie et al, Phys. Rev. Lett. 89, (2002) 4

5 Three main challenges Shaping light direction rather than intensity Controlling nonlinear propagation along lines and tubes for uniform energy deposition Plasma generation and material damage 5

6 Diffraction-free Bessel beams provide a solution Longitudinally extended Bessel beams are an invariant solution to the wave equation Generated from a superposition of plane waves by an axicon 6

7 Single shot machining of glass (Corning 0211) Result 0.65 µj 0.85 µj aspect ratio =100:1 200 nm 330 nm 7

8 Potential practical applications Nanofluidics Nanophotonics Pitch: 0.8 µm Pitch: 1.6 µm Bhuyan et al, Appl. Phys. Lett., 97, (2010) 8

9 Numerical simulations-model Nonlinear Schrödinger equation Dispersion Kerr effect Plasma Plasma absorption defocus. 3-photon ionization Ionization saturation Plasma equation Couairon et al, Eur. Phys. J. Special Topics, 199,1 (2011) 9

10 Numerical simulations We accurately reproduce our experimental results with unphysical collision time! Fluence Plasma density 10

11 3D imaging of filamentation in glass Step by step reconstruction of the intensity distribution C. Xie et al, submitted (2014). Plasma imaging Pump/probe phase imaging Stability Pulse duration Cone angle Bhuyan et al, Appl. Phys. Lett (2014). 11

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13 Origin : plasma and Drude models Plasma Plasma absorption defocus. 2 origins for the deviation: - for the first time within solids, we reach actually plasma phase on nanometric scales (specific non-collisional effects) - Drude model was revisited from first principles: Thesis by N. Schleblanov, St Etienne Results are being recoupled into propagation model. 13

14 Dense plasma formation Plasma densities are close to those observed during fs laser induced micro-explosions. This time on much longer propagation distances. 14

15 Light tubes? Azimuthal Modulation Instability splits the intense ring into several filaments Vinçotte et al, Phys. Rev. Lett. 95, (2005). 15

16 Light tubes? New solution of Propagation-invariant beam : Bessel beam carrying a vortex charge. V. Jukna et al, Opt. Express, accepted (2014). 16

17 Results-high conical angle-stationary regime C. Xie et al, submitted (2014). 17

18 Results-high conical angle-stationary regime We obtain QUANTITATIVE agreement between simulations and experiments Near ablation fluences are reached High losses : deposition of energy into the material Rich dynamics in other regimes 18

19 Towards applications Tubular plasma density and single shot index modification Material compression Guided mode 19

20 Three main challenges Shaping light direction rather than intensity Controlling nonlinear propagation along lines and tubes for uniform energy deposition Plasma generation and material damage 20

21 Three main challenges Shaping light direction rather than intensity Controlling nonlinear propagation along lines and tubes for uniform energy deposition Non diffracting Bessel beams for high aspect ratio drilling Conical structure Accelerating beams for laser machining of curved profiles Caustic structure 21

22 Transverse dimension z (mm) Bending light: accelerating beams We are capable to shape light propagation along arbitrary curves Propagation dimension z (mm) L. Froehly et al., Opt. Express (2011) 22

23 Arbitrary accelerating beams-nonparaxial regime An excellent agreement is then found with the target trajectories highlight: OPN issue "Optics in 2012" "accelerating beyond the horizon" Mathis et al, Opt. Lett., 38, 2218 (2013) 23

24 Curved edge profiling Mathis et al, Appl. Phys. Lett. 101, (2012) Nature Photonics Research Highlights Nov

25 Outcomes We have developed a new approach to control plasma generation at submicron scales over long distances in materials. Ultra-high aspect ratio nanochannels in single shot : 1000:1 was reached. New regime of stable tubular filamentation Highly curved light for laser micro-processing Access to new plasma regime in matter with new models publications, 3 in preparation - 12 invited talks - 1 international patent PCT New projects: - TiSa-TD FP7 project - PICS Univ. Como Italy - new international collaborations 25