Mobility of high-power solitons in saturable nonlinear photonic lattices

We theoretically study the properties of one-dimensional nonlinear saturable photonic lattices exhibiting multiple mobility windows for stationary solutions. The effective energy barrier decreases to a minimum in those power regions where a new intermediate stationary solution appears. As an application, we investigate the dynamics of high-power gaussian-like beams finding several regions where the light transport is enhanced.Comment: 3 pages, 3 figures, to be published in Optics Letter

Transition to miscibility in linearly coupled binary dipolar Bose-Einstein condensates

We investigate effects of dipole-dipole (DD) interactions on immiscibility-miscibility transitions (IMTs) in two-component Bose-Einstein condensates (BECs) trapped in the harmonic-oscillator (HO) potential, with the components linearly coupled by a resonant electromagnetic field (accordingly, the components represent two different spin states of the same atom). The problem is studied by means of direct numerical simulations. Different mutual orientations of the dipolar moments in the two components are considered. It is shown that, in the binary BEC formed by dipoles with the same orientation and equal magnitudes, the IMT cannot be induced by the DD interaction alone, being possible only in the presence of the linear coupling between the components, while the miscibility threshold is affected by the DD interactions. However, in the binary condensate with the two dipolar components polarized in opposite directions, the IMT can be induced \emph{without} any linear coupling. Further, we demonstrate that those miscible and immiscible localized states, formed in the presence of the DD interactions, which are unstable evolve into robust breathers, which tend to keep the original miscibility or immiscibility, respectively. An exception is the case of a very strong DD attraction, when narrow stationary modes are destroyed by the instability. The binary BEC composed of co-polarized dipoles with different magnitudes are briefly considered too.Comment: 10 figure

On bright and dark breathers in lattices with saturable nonlinearity

The moving bright and dark localized modes in one-dimensional optical lattices with saturable nonlinearity are considered with respect to the grand canonical free energy concept and linear stability analysis of the eigenvalue spectra.International School and Conference on Optics and Optical Materials, Sep 03-07, 2007, Belgrade, Serbi

Cancer cell death induced by ruthenium complexes

Summary. Cancer is a complex and often fatal disease characterized by uncontrolled cell division. The most commonly used chemotherapeutics target rapidly dividing cancer cells but, at the same time, damage healthy dividing cells. New metal-based complexes, such as ruthenium complexes, that possess cytotoxic properties, have been developed to overcome these challenges. Ruthenium complexes achieve their antitumor effect mainly by inducing apoptosis. In recent years, induction of other types of cell death, such as ferroptosis and autophagy, was also reported. The dual role of autophagy in cancer cells is a major challenge for the application of metallocomplexes in cancer treatment, either as inducers or inhibitors of autophagy. Also, the effect of ruthenium complexes on other cellular processes such as cell cycle, cell migration, and adhesion are promising approaches in cancer treatment. Our results indicated a significant influence of Ru(II) complexes on these processes in melanoma, cervical and pancreatic cancer. The aim of this review is to summarize the latest data on the effect of ruthenium complexes on different types of cell death

Localized modes in linear flux dressed two-dimensional plus lattice

Flatband (FB) photonic lattices represent ideal testbed for studying transport and localization properties at the linear level in diverse physical systems [1]. Photonic lattices are easy for manipulation and investigation of wave dynamics. The photonic lattices offer an ability to design artificial gauge field effects which are equivalent to the magnetic field flux and the spin-orbit interaction in atomic systems [2]. The two-dimensional (2D) plus lattice [3] dressed by the artificial flux can be experimentally realized by techniques based on the coupled-spring resonators [4] and wave-guide networks [5]. Here we tuned the artificial flux values and studied their effect on the energy band spectrum and we were trying to find compact localized modes (CLMs). The geometry of the uniform plus lattice dressed by the artificial flux is Figure 2. Schematic of 2D plus-like lattice with artificial flux. The unit cell is encircled by a dotted line.schematically presented in Fig. 1. The unit cell consists of five sites, linearly coupled with each other with the same intra-cell coupling constant. The flux of the artificial field modifies the coupling between different unit cell sites to t∙exp(±iϕ/4), where t is the hopping parameter and ϕ is the artificial flux. In the absence of flux, in the uniform lattice, the energy spectrum has one fully degenerate FB, centered at zero, and four dispersive bands (DBs) [3]. We have found that this lattice can host the Aharonov-Bohm effect for certain flux values [6]. When diamond plaquettes are dressed by artificial flux ϕ=π, this lattice spectrum is described by two momentum independent, fully degenerated FBs, and three DBs. Corresponding CLMs have been obtained. In the comparison with the flux-free case, we found three different types of fundamental nonorthogonal CLMs now. These CLMs occupy 5 unit cells i.e. are class U=5. The central site amplitude is zero and all other 4 sites of unit cell have nonzero amplitudes.XVI Photonics Workshop : Book of abstracts; March 12-15, 2023; Kopaonik, Serbi

Higher-band modulational instability in photonic lattices

Propagation of extended Floquet-Bloch modes in the first three bands of a one-dimensional photonic lattice possessing a self-defocusing saturable nonlinearity is studied experimentally and numerically on the example of waveguide arrays in lithium niobate. Discrete modulation instability is observed in all bands in the region of anomalous diffraction, whereas modes propagate stable in the normal diffraction regime

Two-dimensional discrete solitons in dipolar Bose-Einstein condensates

We analyze the formation and dynamics of bright unstaggered solitons in the disk-shaped dipolar Bose-Einstein condensate, which features the interplay of contact (collisional) and long-range dipole-dipole (DD) interactions between atoms. The condensate is assumed to be trapped in a strong optical-lattice potential in the disk's plane, hence it may be approximated by a two-dimensional (2D) discrete model, which includes the on-site nonlinearity and cubic long-range (DD) interactions between sites of the lattice. We consider two such models, that differ by the form of the on-site nonlinearity, represented by the usual cubic term, or more accurate nonpolynomial one, derived from the underlying 3D Gross-Pitaevskii equation. Similar results are obtained for both models. The analysis is focused on effects of the DD interaction on fundamental localized modes in the lattice (2D discrete solitons). The repulsive isotropic DD nonlinearity extends the existence and stability regions of the fundamental solitons. New families of on-site, inter-site and hybrid solitons, built on top of a finite background, are found as a result of the interplay of the isotropic repulsive DD interaction and attractive contact nonlinearity. By themselves, these solutions are unstable, but they evolve into robust breathers which exist on an oscillating background. In the presence of the repulsive contact interactions, fundamental localized modes exist if the DD interaction (attractive isotropic or anisotropic) is strong enough. They are stable in narrow regions close to the anticontinuum limit, while unstable solitons evolve into breathers. In the latter case, the presence of the background is immaterial

Beam interactions in one-dimensional saturable waveguide arrays

The interaction between two parallel beams in one-dimensional discrete saturable systems has been investigated using lithium niobate nonlinear waveguide arrays. When the beams are separated by one channel and in-phase it is possible to observe soliton fusion at low power levels. This new result is confirmed numerically. By increasing the power, soliton-like propagation of weakly-coupled beams occurs. When the beams are out-of-phase the most interesting result is the existence of oscillations which resemble the recently discovered Tamm oscillations.Comment: 5 pages, 6 figures, submitted to Phys. Rev.

Antitumor effect of Ru(II) complex on A375 and HeLa cell growth, migration and adhesion ability

Platinum-based complexes represent the mainstay of treatment for various cancer types. However, their usage is often restricted by numerous side effects or intrinsic and acquired resistance. Therefore, significant research efforts have focused on developing therapeutics based on other transition metals, such as ruthenium 1,2. In this study, effects of transition metal complex, cis-dichlorobis (2,2ʹ-bipyridyl-4,4ʹ-dicarboxylic acid)ruthenium(II) (Ru(II) complex) were analyzed on A375 human melanoma and HeLa cell growth, adhesion ability andmigration. Cell viability assay indicated significant antitumor activity of Ru(II) complex on A375 (~60% of control) up to 72 h after treatment, but not on HeLa cells. However, analysis by clonogenic assay showed that growth of both cell lines was decreased 7 days after treatment. Growth inhibition was followed by G1 phase cell cycle arrest (5–10% G1 increase for A375 and 5–8% for HeLa cells compared to control). Moreover, Ru(II) complex increased adhesivity of A375 and HeLa cells by 11 and 16 % respectively and decreased cell migration, as shown by scratch assay. The obtained results indicate that the analyzed Ru(II) complex is a promising metallodrug, as itinduced growth inhibition of A375 and HeLa cells through induction of G1 arrest and decreased metastatic potential of these cells through the increase ofadhesivity and decrease of cell migration