Milutin Stepić

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.

Light propagation management by disorder and nonlinearity in one-dimensional photonic lattices

We study managing of light beam propagation by competing disorder and nonlinearity in one-dimensional disordered, nonlinear photonic lattices (PLs). The system is modeled by a paraxial time-independent Helmholtz equation, which includes the nonlinear saturable self-interacting term and the quenched or nonquenched disordered PL potential. Diverse PL structures with alternating length of the regular and disordered parts are investigated showing the possibility to change the light propagation from ballistic to the propagation of the transversely localized structures originating from the Anderson-like localization or self-trapping mechanism. Dynamical calculations indicate the possibility of guiding light through the lattice by proper lattice management.

Dynamics of dark solitons localized at structural defect in one-dimensional photonic lattices with defocusing saturable nonlinearity

We investigated the influence of the structural defect placed inside uniform photonic lattice on existence and dynamics of dark spatially localized defect modes. Depending on the strength of the defect and considering the lattice with defocusing saturable nonlinearity, we found two different types of dark solutions to exist. Their stability and dynamical properties are shown to be affected by the defect as well.

Observation of discrete gap solitons in one-dimensional waveguide arrays with alternating spacings and saturable defocusing nonlinearity.

We consider, both experimentally and theoretically, the existence and stability of localized, symmetric, and antisymmetric gap solitons (GSs) in binary lattices of identical waveguides but with alternating spacings. Furthermore, the properties of surface GSs at the boundary of the lattice are explored.

Control of light propagation in one-dimensional quasi-periodic nonlinear photonic lattices

We investigate light localization in quasi-periodic nonlinear photonic lattices (PLs) composed of two periodic component lattices of equal lattice potential strength and incommensurate spatial periods. By including the system parameters from the experimentally realizable setup, we confirm that the light localization is a threshold determined phenomenon in a limit of negligible nonlinearity. In addition, we show that self-trapping can affect the localized light in the established setup only in the presence of strong nonlinearity. Guided by these findings we consider the possibility of governing light propagation by proposing a composite lattice system comprising alternating quasi-periodic parts with different potential depths and nonlinearity strengths.

Linear and nonlinear light propagation at the interface of two homogeneous waveguide arrays

We investigate linear and nonlinear light propagation at the interface of two one-dimensional homogeneous waveguide arrays containing a single defect of different strength. For the linear case and in a limited region of the defect size, we find trapped staggered and unstaggered modes. In the nonlinear case, we study the dependence of power thresholds for discrete soliton formation in different channels as a function of defect strength. All experimental results are confirmed theoretically using an adequate discrete model.

Defect induced wave-packet dynamics in linear one-dimensional photonic lattices

We study numerically light beam propagation across uniform, linear, one-dimensional photonic lattice possessing one nonlinear defect. Depending on the strength of nonlinear defect, input beam position and phase shift, different dynamical regimes have been identified. We distinguish input parameters set for which a regime of light propagation blockade by the nonlinear defect appears. Obtained results may be useful for all-optical control of transmission of waves in interferometry.

The influence of nonlinear and linear defects on the light propagation through linear one-dimensional photonic lattice

In this paper, the light beam propagation through one-dimensional photonic lattice, possessing one nonlinear defect and one linear defect, has been investigated numerically. Different dynamical regimes have been identified in terms of the distance between the two defects, position of the incident light beam, the width of linear defect, the values of nonlinearity and presence of the transverse kick. Strong localized modes on the defects, breathing and zig-zag modes in the area between defects have been observed. It has been concluded that the width of the linear defect placed next to the nonlinear one influences localization of the beam at the nonlinear waveguide. On the other hand, the nonlinear defect, regardless of the values of nonlinearity, have a small influence on the beam propagation in photonic lattice. It has been observed that the transverse kick of the initial beam leads to the distortion of localized structures. By launching the light beam towards defects, the reflection of light has been noticed. Presented results can be useful for different applications, such as blocking, filtering and routing of light beam through optical media.

Light propagation management in complex photonic lattices

Here, an overview of the main results for light propagation and control over it in composite complex photonic lattices based on photorefractive materials is presented.

Novel type of one-dimensional discrete vector solitons

Discrete vector solitons (DVS) are a special class of vector solitons which have been found to exist in discrete media such as, for example, nonlinear waveguide arrays. Individual components of such complex structure are unable to form stable localized structures on their own. In this contribution we explore the DVS in NWA with saturable nonlinearity in a special case in which the components of DVS have the same frequency but differ in polarization.