High aspect ratio micro-explosions in the bulk of sapphire generated by femtosecond Bessel beams.
Femtosecond pulses provide an extreme degree of confinement of light matter-interactions in high-bandgap materials because of the nonlinear nature of ionization. It was recognized very early on that a highly focused single pulse of only nanojoule energy could generate spherical voids in fused silica and sapphire crystal as the nanometric scale plasma generated has energy sufficient to compress the material around it and to generate new material phases. But the volumes of the nanometric void and of the compressed material are extremely small. Here we use single femtosecond pulses shaped into high-angle Bessel beams at microjoule energy, allowing for the creation of very high 100:1 aspect ratio voids in sapphire crystal, which is one of the hardest materials, twice as dense as glass. The void volume is 2 orders of magnitude higher than those created with Gaussian beams. Femtosecond and picosecond illumination regimes yield qualitatively different damage morphologies. These results open novel perspectives for laser processing and new materials synthesis by laser-induced compression.
Institut FEMTO-ST, UMR 6174 CNRS Université Bourgogne Franche-Comté, 25030 Besancon Cedex, France.
L
L
Rapp
Institut FEMTO-ST, UMR 6174 CNRS Université Bourgogne Franche-Comté, 25030 Besancon Cedex, France.
R
R
Meyer
Institut FEMTO-ST, UMR 6174 CNRS Université Bourgogne Franche-Comté, 25030 Besancon Cedex, France.
R
R
Giust
Institut FEMTO-ST, UMR 6174 CNRS Université Bourgogne Franche-Comté, 25030 Besancon Cedex, France.
L
L
Furfaro
Institut FEMTO-ST, UMR 6174 CNRS Université Bourgogne Franche-Comté, 25030 Besancon Cedex, France.
M
M
Jacquot
Institut FEMTO-ST, UMR 6174 CNRS Université Bourgogne Franche-Comté, 25030 Besancon Cedex, France.
P A
PA
Lacourt
Institut FEMTO-ST, UMR 6174 CNRS Université Bourgogne Franche-Comté, 25030 Besancon Cedex, France.
J M
JM
Dudley
Institut FEMTO-ST, UMR 6174 CNRS Université Bourgogne Franche-Comté, 25030 Besancon Cedex, France.
F
F
Courvoisier
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