FOTONICA - Grup de Recerca de Fotònica
http://hdl.handle.net/2117/3270
Tue, 25 Jul 2017 12:52:09 GMT2017-07-25T12:52:09ZSteering and switching of soliton-like beams via interaction in a nanocolloid with positive polarizability
http://hdl.handle.net/2117/106613
Steering and switching of soliton-like beams via interaction in a nanocolloid with positive polarizability
Salazar Romero, M. Y.; Ayala, Y. A.; Brambila, E.; Lopez Peña, L. A.; Sciberras, L.; Minzoni, A. A.; Terborg, Roland A.; Pérez Torres, Juan; Volke-Sepulveda, Karen
We unveil different regimes for the interaction between two orthogonally polarized soliton-like beams in a colloidal suspension of nanoparticles with positive polarizability. The interaction is always attractive. However, it noticeably changes as a function of the angle and the power distribution between the input beams. For small angles, both interacting solitons fuse into a single entity, whose propagation direction can be continuously steered. As the interaction angle increases, the resulting self-collimated beam can be practically switched between two positions when the power imbalance between the beams is changed. For interaction angles larger than ~10°~10°, the result is no longer a single emerging soliton when the input power is balanced between the two beams.
Wed, 19 Jul 2017 10:45:48 GMThttp://hdl.handle.net/2117/1066132017-07-19T10:45:48ZSalazar Romero, M. Y.Ayala, Y. A.Brambila, E.Lopez Peña, L. A.Sciberras, L.Minzoni, A. A.Terborg, Roland A.Pérez Torres, JuanVolke-Sepulveda, KarenWe unveil different regimes for the interaction between two orthogonally polarized soliton-like beams in a colloidal suspension of nanoparticles with positive polarizability. The interaction is always attractive. However, it noticeably changes as a function of the angle and the power distribution between the input beams. For small angles, both interacting solitons fuse into a single entity, whose propagation direction can be continuously steered. As the interaction angle increases, the resulting self-collimated beam can be practically switched between two positions when the power imbalance between the beams is changed. For interaction angles larger than ~10°~10°, the result is no longer a single emerging soliton when the input power is balanced between the two beams.Spatial Solitons in Quadratic Nonlinear Media
http://hdl.handle.net/2117/105851
Spatial Solitons in Quadratic Nonlinear Media
Torner Sabata, Lluís
Mon, 26 Jun 2017 08:50:47 GMThttp://hdl.handle.net/2117/1058512017-06-26T08:50:47ZTorner Sabata, LluísBloch-wave packet control in truncated modulated optical lattices
http://hdl.handle.net/2117/105837
Bloch-wave packet control in truncated modulated optical lattices
Kartashov, Yaroslav V.; Vysloukh, Victor A.; Torner Sabata, Lluís
We study the reflection of Bloch wave packets at the interface of an optical lattice possessing a shallow longitudinal out-of-phase refractive index modulation in the adjacent waveguides. We show that the relation between the transmitted and reflected energy flows can be efficiently controlled by tuning the frequency and depth of the modulation. Thus, complete beam reflection may be achieved for a set of resonant modulation frequencies at which light tunneling between adjacent guides of modulated lattice is inhibited.
Mon, 26 Jun 2017 06:34:21 GMThttp://hdl.handle.net/2117/1058372017-06-26T06:34:21ZKartashov, Yaroslav V.Vysloukh, Victor A.Torner Sabata, LluísWe study the reflection of Bloch wave packets at the interface of an optical lattice possessing a shallow longitudinal out-of-phase refractive index modulation in the adjacent waveguides. We show that the relation between the transmitted and reflected energy flows can be efficiently controlled by tuning the frequency and depth of the modulation. Thus, complete beam reflection may be achieved for a set of resonant modulation frequencies at which light tunneling between adjacent guides of modulated lattice is inhibited.Vortex lattice solitons supported by localized gain
http://hdl.handle.net/2117/105835
Vortex lattice solitons supported by localized gain
Kartashov, Yaroslav V.; Konotop, Vladimir V; Vysloukh, Victor A.; Torner Sabata, Lluís
We show that localized gain supports the existence of dissipative vortex solitons in periodic Kerr media with strong two-photon absorption. Vortex solitons exist in both focusing and defocusing media, with their propagation constants emerging from semi-infinite or finite gaps in the lattice spectrum. Coincidence of the discrete rotational symmetries of the gain landscape and refractive index distribution is a necessary condition for exciting vortex solitons, which otherwise transform into stable dissipative multipoles.
Mon, 26 Jun 2017 06:29:45 GMThttp://hdl.handle.net/2117/1058352017-06-26T06:29:45ZKartashov, Yaroslav V.Konotop, Vladimir VVysloukh, Victor A.Torner Sabata, LluísWe show that localized gain supports the existence of dissipative vortex solitons in periodic Kerr media with strong two-photon absorption. Vortex solitons exist in both focusing and defocusing media, with their propagation constants emerging from semi-infinite or finite gaps in the lattice spectrum. Coincidence of the discrete rotational symmetries of the gain landscape and refractive index distribution is a necessary condition for exciting vortex solitons, which otherwise transform into stable dissipative multipoles.Spectral tunneling of lattice nonlocal solitons
http://hdl.handle.net/2117/105802
Spectral tunneling of lattice nonlocal solitons
Kartashov, Yaroslav V.; Vysloukh, Victor A.; Torner Sabata, Lluís
We address spectral tunneling of walking spatial solitons in photorefractive media with nonlocal diffusion of the nonlinear response and an imprinted shallow optical lattice. In contrast to materials with local nonlinearities, where solitons travelling across the lattice close to the Bragg angle suffer large radiative losses, in photorefractive media with diffusion nonlinearity resulting in self-bending solitons survive when their propagation angle approaches and even exceeds the Bragg angle. In the spatial frequency domain this effect can be considered as tunneling through the band of spatial frequencies centered around the Bragg frequency where the spatial group velocity dispersion is positive.
Fri, 23 Jun 2017 12:02:50 GMThttp://hdl.handle.net/2117/1058022017-06-23T12:02:50ZKartashov, Yaroslav V.Vysloukh, Victor A.Torner Sabata, LluísWe address spectral tunneling of walking spatial solitons in photorefractive media with nonlocal diffusion of the nonlinear response and an imprinted shallow optical lattice. In contrast to materials with local nonlinearities, where solitons travelling across the lattice close to the Bragg angle suffer large radiative losses, in photorefractive media with diffusion nonlinearity resulting in self-bending solitons survive when their propagation angle approaches and even exceeds the Bragg angle. In the spatial frequency domain this effect can be considered as tunneling through the band of spatial frequencies centered around the Bragg frequency where the spatial group velocity dispersion is positive.Stabilization of two-dimensional solitons in cubic-saturable nonlinear lattices
http://hdl.handle.net/2117/105800
Stabilization of two-dimensional solitons in cubic-saturable nonlinear lattices
Borovkova, Olga V.; Kartashov, Yaroslav; Torner Sabata, Lluís
We consider soliton dynamics and stability in a nonlinear lattice formed by alternating domains with focusing cubic and saturable nonlinearities. We find that in such lattices, solitons centered on cubic domains may be stabilized even in two-dimensional geometries, in spite of their intrinsic catastrophic instability in the absence of the lattice. Solitons centered on saturable domains are always unstable.
Fri, 23 Jun 2017 11:58:06 GMThttp://hdl.handle.net/2117/1058002017-06-23T11:58:06ZBorovkova, Olga V.Kartashov, YaroslavTorner Sabata, LluísWe consider soliton dynamics and stability in a nonlinear lattice formed by alternating domains with focusing cubic and saturable nonlinearities. We find that in such lattices, solitons centered on cubic domains may be stabilized even in two-dimensional geometries, in spite of their intrinsic catastrophic instability in the absence of the lattice. Solitons centered on saturable domains are always unstable.Dissipative defect modes in periodic structures
http://hdl.handle.net/2117/105799
Dissipative defect modes in periodic structures
Kartashov, Yaroslav; Konotop, Vladimir V; Vysloukh, Victor A.; Torner Sabata, Lluís
We show that periodic optical lattices imprinted in cubic nonlinear media with strong two-photon absorption and localized linear gain landscapes support stable dissipative defect modes in both focusing and defocusing media. Their shapes and transverse extent are determined by the propagation constant that belongs to a gap of the lattice spectrum, which, in turn, is determined by the relation between gain and losses. One-hump and two-hump dissipative defect modes are obtained.
Fri, 23 Jun 2017 11:55:41 GMThttp://hdl.handle.net/2117/1057992017-06-23T11:55:41ZKartashov, YaroslavKonotop, Vladimir VVysloukh, Victor A.Torner Sabata, LluísWe show that periodic optical lattices imprinted in cubic nonlinear media with strong two-photon absorption and localized linear gain landscapes support stable dissipative defect modes in both focusing and defocusing media. Their shapes and transverse extent are determined by the propagation constant that belongs to a gap of the lattice spectrum, which, in turn, is determined by the relation between gain and losses. One-hump and two-hump dissipative defect modes are obtained.Wave localization at the boundary of disordered photonic lattices
http://hdl.handle.net/2117/105798
Wave localization at the boundary of disordered photonic lattices
Szameit, Alexander; Kartashov, Yaroslav V.; Zeil, P.; Dreisow, Felix; Heinrich, Matthias; Keil, R.; Nolte, Stefan; Tünnermann, A.; Vysloukh, Victor A.; Torner Sabata, Lluís
We report on the experimental observation of reduced light-energy transport and disorder-induced localization close to a boundary of a truncated 1D disordered photonic lattice. Our observations uncover that a higher level of disorder near the boundary is required to obtain similar localization than in the bulk.
Fri, 23 Jun 2017 11:52:39 GMThttp://hdl.handle.net/2117/1057982017-06-23T11:52:39ZSzameit, AlexanderKartashov, Yaroslav V.Zeil, P.Dreisow, FelixHeinrich, MatthiasKeil, R.Nolte, StefanTünnermann, A.Vysloukh, Victor A.Torner Sabata, LluísWe report on the experimental observation of reduced light-energy transport and disorder-induced localization close to a boundary of a truncated 1D disordered photonic lattice. Our observations uncover that a higher level of disorder near the boundary is required to obtain similar localization than in the bulk.Twin-vortex solitons in nonlocal nonlinear media
http://hdl.handle.net/2117/105793
Twin-vortex solitons in nonlocal nonlinear media
Fangwei, Ye; Kartashov, Yaroslav V.; Hu, Bambi; Torner Sabata, Lluís
We consider soliton formation in thermal nonlinear media bounded by rectangular cross sections and uncover what we believe to be a new class of nonlinear stationary topological state. Specifically, we find that stationary higher-order vortex states in standard shapes do not exist, but rather they take the form of multiple spatially separated single-charge singularities nested in an elliptical beam. Double-charge states are found to be remarkably robust despite their shape asymmetry and phase-singularity splitting. States with higher topological charges are found to be unstable.
Fri, 23 Jun 2017 11:47:47 GMThttp://hdl.handle.net/2117/1057932017-06-23T11:47:47ZFangwei, YeKartashov, Yaroslav V.Hu, BambiTorner Sabata, LluísWe consider soliton formation in thermal nonlinear media bounded by rectangular cross sections and uncover what we believe to be a new class of nonlinear stationary topological state. Specifically, we find that stationary higher-order vortex states in standard shapes do not exist, but rather they take the form of multiple spatially separated single-charge singularities nested in an elliptical beam. Double-charge states are found to be remarkably robust despite their shape asymmetry and phase-singularity splitting. States with higher topological charges are found to be unstable.Observation of two-dimensional superlattice solitons
http://hdl.handle.net/2117/105791
Observation of two-dimensional superlattice solitons
Heinrich, Matthias; Kartashov, Yaroslav; Ramírez, L. P. R.; Szameit, Alexander; Dreisow, Felix; Keil, R; Nolte, Stefan; Tünnermann, Andreas; Vysloukh, Victor A.; Torner Sabata, Lluís
We observe experimentally two-dimensional solitons in superlattices comprising alternating deep and shallow waveguides fabricated via the femtosecond-laser direct writing technique. We find that the symmetry of linear diffraction patterns as well as soliton shapes and threshold powers largely differ for excitations centered on deep and shallow sites. Thus, bulk and surface solitons centered on deep waveguides require much lower powers than their counterparts on shallow sites.
Fri, 23 Jun 2017 11:38:52 GMThttp://hdl.handle.net/2117/1057912017-06-23T11:38:52ZHeinrich, MatthiasKartashov, YaroslavRamírez, L. P. R.Szameit, AlexanderDreisow, FelixKeil, RNolte, StefanTünnermann, AndreasVysloukh, Victor A.Torner Sabata, LluísWe observe experimentally two-dimensional solitons in superlattices comprising alternating deep and shallow waveguides fabricated via the femtosecond-laser direct writing technique. We find that the symmetry of linear diffraction patterns as well as soliton shapes and threshold powers largely differ for excitations centered on deep and shallow sites. Thus, bulk and surface solitons centered on deep waveguides require much lower powers than their counterparts on shallow sites.