Rotating vector solitary waves in isotropic fibers

Two-color pulse compounds in waveguides with a zero-nonlinearity point

We study incoherently coupled two-frequency pulse compounds in waveguides with single zero-dispersion and zero-nonlinearity points. In such waveguides, supported by a negative nonlinearity, soliton dynamics can be obtained even in domains of normal dispersion. We demonstrate trapping of weak pulses by solitary-wave wells, forming nonlinear-photonics meta-atoms, and molecule-like bound-states of pulses. We study the impact of the Raman effect on these pulse compounds, finding that, depending on the precise subpulse configuration, they decelerate, accelerate, or are completely unaffected. Our results extend the range of systems in which two-frequency pulse compounds can be expected to exist and demonstrate further unique and unexpected behavior.

Polarization evolution of vector wave amplitudes in twisted fibers pumped by single and paired pulses

Nonlinear polarization dynamics of single and paired pulses in twisted fibers is experimentally and numerically studied. Accompanying a dramatic difference in the output spectrum when a single- or double-amplified soliton pulse is launched in the fiber, the output polarization for the two cases also reveals very different characteristics.

Polarisation dynamics of vector soliton molecules in mode locked fibre laser

Two fundamental laser physics phenomena - dissipative soliton and polarisation of light are recently merged to the concept of vector dissipative soliton (VDS), viz. train of short pulses with specific state of polarisation (SOP) and shape defined by an interplay between anisotropy, gain/loss, dispersion, and nonlinearity. Emergence of VDSs is both of the fundamental scientific interest and is also a promising technique for control of dynamic SOPs important for numerous applications from nano-optics to high capacity fibre optic communications. Using specially designed and developed fast polarimeter, we present here the first experimental results on SOP evolution of vector soliton molecules with periodic polarisation switching between two and three SOPs and superposition of polarisation switching with SOP precessing. The underlying physics presents an interplay between linear and circular birefringence of a laser cavity along with light induced anisotropy caused by polarisation hole burning.

Experimental investigation of the extraction of solitons at the initial stage of the soliton formation process

We demonstrate the extraction of a single soliton from a bunch of solitons generated by the pulse breakup effect. The bunch of solitons was generated in a 500-m fiber pumped by 25-ps pulses. For the extraction of single soliton from the bunch we use a nonlinear optical loop mirror (NOLM). At its output we detected a pulse with full width at half-maximum (FWHM) of 0.99 ps whose autocorrelation trace corresponds to that of a soliton. Our results demonstrate that the suggested method can be useful for soliton generation, and also for investigations of the initial stage of the soliton formation process.

Polarization dynamics of the fundamental vector soliton of isotropic Kerr media

We characterize fully the polarization dynamics of the fundamental vector soliton of isotropic Kerr materials by measuring the Stokes parameters of an elliptically polarized self-trapped optical beam propagating in a slab planar waveguide. Our experiment clearly shows that this two-component spatial vector soliton exhibits both the so-called ellipse rotation and curved-shape ellipticity that are due to the self-induced nonlinear birefringence between the two components of the vector soliton. The polarization of the vector soliton is accurately determined both in the transverse and longitudinal directions and comparisons with numerical simulations based on two coupled nonlinear Schrödinger equations provide an excellent quantitative agreement. Spatiotemporal numerical simulations that take into account the finite pulse duration of the experimental input optical beam must, however, be used to match rigorously the measured state of polarization of the vector soliton.

Discrete vector solitons in Kerr nonlinear waveguide arrays

We report the first experimental observation of discrete vector solitons in AlGaAs nonlinear waveguide arrays. These self-trapped states are possible through the coexistence of two orthogonally polarized fields and are stable in spite of the presence of four-wave mixing effects. We demonstrate that at sufficiently high power levels the two polarizations lock into a highly localized vector discrete soliton that would have been otherwise impossible in the absence of either one of these two components.

Symmetry-breaking instability of multimode vector solitons

We show experimentally that the two-component multimode spatial optical vector soliton, i.e., a two-hump self-guided laser beam, exhibits in Kerr media a sharp space-inversion symmetry-breaking instability. The experiment is performed in a CS2 planar waveguide using the orthogonal circular polarization states of light as the two components of the vector soliton.

Radiative losses due to pulse interactions in birefringent nonlinear optical fibers

The transient evolution of two-polarization pulses in a birefringent nonlinear optical fiber, governed by coupled nonlinear Schrödinger (NLS) equations, is considered. The evolution is studied using a trial function consisting of coupled solitonlike pulses with varying parameters augmented by a radiative shelf in the Lagrangian formulation of the coupled equations, which yields ordinary differential equations for the pulse parameters. It is shown that including mass and momentum fluxes due to the radiative shelf is a requirement to obtain good agreement with full numerical solutions of the governing equations.

Light propagation through birefringent, nonlinear media with deep gratings

We present a theory that includes birefringence in the description of one-dimensional photonic band-gap materials with a Kerr nonlinearity. The Bloch functions in the absence of nonlinearity completely characterize the linear problem, for deep as well as shallow gratings, and the method of multiple scales is used to include the effects of nonlinearity and finite optical pulse length. We derive two sets of equations appropriate in different frequency regimes, a set of coupled mode equations and a set of coupled nonlinear Schrodinger equations; we investigate the connections between these equations and where their regimes of validity overlap. Finally, we use our results to describe energy exchange between polarization modes in a birefringent medium.

Linear stability analysis of walking vector solitons

The linear stability analysis of two-parameter families of walking vector solitons of coupled nonlinear Schrödinger equations is performed. It is shown that the eigenvalues of the corresponding linearized problem can be complex valued in certain regions of the parameter space. The complex nature of the associated Lyapunov eigenvalues leads to a quite complicated pattern of instability regions of lowest-order soliton types. This pattern includes two typical situations: (i) the relevant eigenmode has a purely imaginary eigenvalue that passes through zero at the critical point and then becomes purely real, and (ii) the interplay between two discrete eigenmodes having purely imaginary eigenvalues leads to a bifurcation scenario where two imaginary eigenvalues merge together and become complex at the bifurcation point. It is shown that all known, lowest-order soliton types, namely slow, fast, in-phase vector, and out-of-phase vector, are dynamically stable in certain regions of the parameter space.

Nonlinear pulse propagation in birefringent fiber Bragg gratings

We present two sets of equations to describe nonlinear pulse propagation in a birefringent fiber Bragg grating. The first set uses a coupled-mode formalism to describe light in or near the photonic band gap of the grating. The second set is a pair of coupled nonlinear Schroedinger equations. We use these equations to examine viable switching experiments in the presence of birefringence. We show how the birefringence can both aid and hinder device applications.