Solange B. Cavalcanti

Modulational instability in semiconductor-doped glass fibers with saturable nonlinearity

Modulational instability in doped glass fibers is analyzed theoretically in a steady-state regime, taking into account a saturable nonlinearity. The results have shown that the critical modulation frequency and modulation gain increase with input power, reaching a maximum value at the saturation power. This leads to a unique value of the critical modulation frequency for two different input powers so that two solutions will experience a maximum gain at the same frequency.

Plasmon polaritons in photonic superlattices containing a left-handed material

We analyze one-dimensional photonic superlattices which alternate layers of air and a left-handed material. We assume Drude-type dispersive responses for the dielectric permittivity and magnetic permeability of the left-handed material. Maxwells equations and the transfer-matrix technique are used to derive the dispersion relation and transmission spectra for the propagation of obliquely incident optical fields. The photonic dispersion indicates that the growth direction component of the electric (or magnetic) field leads to the propagation of electric (or magnetic) plasmon polaritons, for either TE or TM configurations. Furthermore, we show that if the plasma frequency is chosen within the photonic n(ω)=0 zeroth-order bandgap, the coupling of light with plasmons weakens considerably. As light propagation is forbidden in that particular frequency region, the plasmon-polariton mode reduces to a pure plasmon mode.

Suppression of Anderson localization of light and Brewster anomalies in disordered superlattices containing a dispersive metamaterial

Light propagation through 1D disordered structures composed of alternating layers, with random thicknesses, of air and a dispersive metamaterial is theoretically investigated. Both normal and oblique incidences are considered. By means of numerical simulations and an analytical theory, we have established that Anderson localization of light may be suppressed: (i) in the long wavelength limit, for a finite angle of incidence which depends on the parameters of the dispersive metamaterial; (ii) for isolated frequencies and for specific angles of incidence, corresponding to Brewster anomalies in both positive- and negative-refraction regimes of the dispersive metamaterial. These results suggest that Anderson localization of light could be explored to control and tune light propagation in disordered metamaterials.

Resonant Zener tunneling in two-dimensional periodic photonic lattices

We study Zener tunneling in two-dimensional photonic lattices and derive, for the case of hexagonal symmetry, the generalized Landau-Zener-Majorana model describing resonant interaction between high-symmetry points of the photonic spectral bands. We demonstrate that this effect can be employed for the generation of Floquet-Bloch modes and verify the model by direct numerical simulations of the tunneling effect.

Space-time break-up in the self-focusing of ultrashort pulses

We investigate the effect of rapidly varying perturbations on the initial stage of the three-dimensional propagation of ultrashort pulses through a nonlinear dispersive medium, in the limit and beyond the slowly varying envelope approximation. We have found a space-time coupling effect which distorts and reduces the range for which sidebands appear on far-field and temporal spectrum.

Modulation instability of ultrashort pulses via a generalized nonlinear Schrödinger equation with deviating argument

Abstract A modified nonlinear Schrodinger equation is proposed to describe the propagation of ultrashort optical pulses through a dispersive medium with inertial nonlinearity. From this equation we derive quite simply the initial growth rates of the sidebands corresponding to the modulational and four-wave mixing instabilities as well as the Raman interaction for modulational frequencies of the order of the Raman gain spectrum.

Zener tunneling in two-dimensional photonic lattices

We discuss the interband light tunneling in a two-dimensional periodic photonic structure, as studied recently in experiments for optically induced photonic lattices [Trompeter, Phys. Rev. Lett. 96, 053903 (2006)]. We identify the Zener tunneling regime at the crossing of two Bloch bands, which occurs in the generic case of a Bragg reflection when the Bloch index crosses the edge of the irreducible Brillouin zone. Similarly, higher-order Zener tunneling involves four Bloch bands when the Bloch index passes through a high-symmetry point on the edge of the Brillouin zone. We derive simple analytical models that describe the tunneling effect, and calculate the corresponding tunneling probabilities.

Optical spin-to-orbital plasmonic angular momentum conversion in subwavelength apertures

Within the framework of the Huygens-Fresnel approach, we evaluate the coherent superposition of surface plasmon (SP) modes excited by an incident circularly polarized light propagating through an array of subwavelength holes. Numerical results of the plasmonic distribution exhibit a rich structure that reveals the creation and annihilation of vortex arrays in the field phase. These phase singularities stem from total transfer of the spin angular momentum (AM) of the incident radiation to the orbital AM of the SP.

Bulk plasmon polariton-gap soliton-induced transparency in one-dimensional Kerr-metamaterial superlattices.

We have performed a theoretical study of various arrangements of one-dimensional heterostructures composed by bilayers made of nondispersive (A)/dispersive linear (B) materials and illuminated by an obliquely incident electromagnetic wave, which are shown to exhibit a robust bulk-like plasmon-polariton gap for frequencies below the plasma frequency. The origin of this gap stems from the coupling between photonic and plasmonic modes that may be of a magnetic (electric) origin in a transversal electric (traversal magnetic) configuration yielding a plasmon-polariton mode. By substituting the nondispersive linear layer by a nonlinear Kerr layer, we have found that, for frequencies close to the edge of the plasmon-polariton gap, the transmission of a finite superlattice presents a multistable behavior and it switches from very low values to the maximum transparency at particular values of the incident power. At these frequencies, for those singular points where transmission becomes maximum, we find localized plasmon-polariton-gap solitons of various orders depending on the particular value of the incident power. Present results reveal, therefore, new gap plasmon-soliton solutions that are hybrid modes stemming from the resonant coupling between the incoming electromagnetic wave and the plasmonic modes of the dispersive material, leading to the transparency of a stack with nonlinear inclusions.

Absorption effects on plasmon polaritons in quasiperiodic photonic superlattices containing a metamaterial

Absorption effects on plasmon-polariton excitations in quasiperiodic (Fibonacci and Thue-Morse) one-dimensional stacks composed of layers of right- and left-handed materials are theoretically investigated. A Drude-type dispersive response for both the dielectric permittivity and magnetic permeability of the left-handed layer is considered. Maxwells equations are solved for oblique incidence by using the transfer matrix formalism, and the reflection coefficient as a function of the frequency and incidence angle is obtained. The Fibonacci (or Thue-Morse) quasiperiodic structure leads to a Cantor-like photonic spectra for the plasmon-polariton modes. Moreover, results for the photonic band structure, density of states and reflection coefficient indicate that plasmon-polariton modes are robust in the presence of low and moderate levels of absorption.