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Couairon A.,Ecole Polytechnique - Palaiseau | Lotti A.,Ecole Polytechnique - Palaiseau | Lotti A.,University delInsubria | Panagiotopoulos P.,Foundation for Research and Technology Hellas | And 5 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

We investigate the nonlinear propagation of intense Airy beams forming filaments in transparent media. We demonstrate the existence of stationary nonlinear Airy beams in a planar geometry. These beams preserve the intensity profile and the transverse acceleration of the Airy peak. We show that stationary propagation is sustained by a continuous energy flux to the main Airy lobe from its neighbors. For powers in the main Airy lobe exceeding a certain threshold, this stationary propagation regime becomes unstable. We extend our results to the 2-dimensional case: Airy beams with high powers in the main lobe reshape into a multifilamentary pattern induced by Kerr and multiphoton nonlinearities. The nucleation of new filaments and their interaction, affects the acceleration of the main Airy lobes. Experiments performed in water corroborate the existence of these two regimes. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE). Source


Couairon A.,Ecole Polytechnique - Palaiseau | Lotti A.,Ecole Polytechnique - Palaiseau | Lotti A.,University delInsubria | Panagiotopoulos P.,Foundation for Research and Technology Hellas | And 9 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

We investigate the nonlinear propagation of intense Bessel and Airy beams forming filaments in transparent media. We identify two propagation regimes separated by the relative importance of multiphoton absorption and self-focusing of the main Bessel or Airy lobe, due to the Kerr effect. We show that intense Bessel or Airy beams are reshaped into stationary nonlinear beams whose propagation is sustained by a continuous energy ux to the main lobe from its neighbors. The stationary propagation regime is obtained for Bessel cone angles exceeding a certain threshold, by focusing a Gaussian beam of suficient power with an axicon. With respect to linear Bessel beams, stationnary nonlinear Bessel beams exhibit ring compression and attenuation of contrast. For small cone angles, the nonlinear Bessel beams become unstable leading to an unsteady propagation regime. We demonstrate similar physics for intense Airy beam freely propagating in a Kerr medium: stationary nonlinear Airy beams are demonstrated in a planar geometry. These beams preserve the intensity profile and the transverse acceleration of the Airy peak. For powers in the main Airy lobe exceeding a certain threshold, this stationary propagation regime becomes unstable. In the 2-dimensional case, Airy beams with high powers in the main lobe reshape into a multifilamentary pattern induced by Kerr and multiphoton nonlinearities. The nucleation of new filaments and their interaction, affects the acceleration of the main Airy lobes. © 2013 SPIE. Source


Lotti A.,University delInsubria | Lotti A.,Ecole Polytechnique - Palaiseau | Faccio D.,University delInsubria | Faccio D.,Heriot - Watt University | And 7 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We demonstrate the existence of an additional class of stationary accelerating Airy wave forms that exist in the presence of third-order (Kerr) nonlinearity and nonlinear losses. Numerical simulations and experiments, in agreement with the analytical model, highlight how these stationary solutions sustain the nonlinear evolution of Airy beams. The generic nature of the Airy solution allows extension of these results to other settings, and a variety of applications are suggested. © 2011 American Physical Society. Source


Bava A.,University delInsubria | Gornati R.,Polytechnic of Milan | Cappellini F.,University delInsubria | Caldinelli L.,University delInsubria | And 5 more authors.
Nanomedicine | Year: 2013

Aim: The authors propose a new magnetic nanoparticle-enzyme system for cancer therapy capable of targeting the enzyme and consequently decreasing the adverse effects, meanwhile improving the patients life quality. Materials & methods: The authors have functionalized Fe3O4 nanoparticles with 3-amino-propyltriethoxysilane (APTES) and conjugated it to yeast D-amino acid oxidase (DAAO) by coupling this with glutaraldehyde. Results & conclusion: The authors have tested the Fe3O 4-APTES-DAAO system on three tumor cell lines. Exposed cells show, at the electron microscope level, nanoparticles on the surface of the plasma membrane and inside endocytic vesicles. Fe3O4-APTES-DAAO caused a substantial decrease of cell viability greatly augmented when D-alanine, a DAAO substrate, was added. Fe3O4-APTES-DAAO was demonstrated to be more effective than free DAAO, confirming the validity of the system in cancer therapy. © 2013 Future Medicine Ltd. Source

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