Time-reversal focusing of an expanding soliton gas in disordered replicas

We investigate the properties of time reversibility of a soliton gas, originating from a dispersive regularization of a shock wave, as it propagates in a strongly disordered environment. An original approach combining information measures and spin glass theory shows that time reversal focusing occurs for different replicas of the disorder in forward and backward propagation, provided the disorder varies on a length scale much shorter than the width of the soliton constituents. The analysis is performed by starting from a new class of reflectionless potentials, which describe the most general form of an expanding soliton gas of the defocusing nonlinear Schroedinger equation.Comment: 7 Pages, 6 Figure

Time-reversal focusing of an expanding soliton gas in disordered replicas

We investigate the properties of time reversibility of a soliton gas, originating from a dispersive regularization of a shock wave, as it propagates in a strongly disordered environment. An original approach combining information measures and spin glass theory shows that time reversal focusing occurs for different replicas of the disorder in forward and backward propagation, provided the disorder varies on a length scale much shorter than the width of the soliton constituents. The analysis is performed by starting from a new class of reflectionless potentials, which describe the most general form of an expanding soliton gas of the defocusing nonlinear Schroedinger equation.Comment: 7 Pages, 6 Figure

Bistable Helmholtz dark spatial optical solitons in materials with self-defocusing saturable nonlinearity

We present, to the best of our knowledge, the first exact dark spatial solitons of a nonlinear Helmholtz equation with a self-defocusing saturable refractive-index model. These solutions capture oblique (arbitrary-angle) propagation in both the forward and backward directions, and they can also exhibit a bistability characteristic. A detailed derivation is presented, obtained by combining coordinate transformations and direct-integration methods, and the corresponding solutions of paraxial theory are recovered asymptotically as a subset. Simulations examine the robustness of the new Helmholtz solitons, with stationary states emerging from a range of perturbed input beams

Bistable Helmholtz dark spatial optical solitons in materials with self-defocusing saturable nonlinearity

We present, to the best of our knowledge, the first exact dark spatial solitons of a nonlinear Helmholtz equation with a self-defocusing saturable refractive-index model. These solutions capture oblique (arbitrary-angle) propagation in both the forward and backward directions, and they can also exhibit a bistability characteristic. A detailed derivation is presented, obtained by combining coordinate transformations and direct-integration methods, and the corresponding solutions of paraxial theory are recovered asymptotically as a subset. Simulations examine the robustness of the new Helmholtz solitons, with stationary states emerging from a range of perturbed input beams

Limits of the uni-directional pulse propagation approximation

I apply the method of characteristics to both bi-directional and uni-directional pulse propagation in dispersionless media containing nonlinearity of arbitrary order. The differing analytic predictions for the shocking distance quantify the effects of the uni-directional approximation used in many pulse propagation models. Results from numerical simulations support the theoretical predictions, and reveal the nature of the coupling between forward and backward waves.Comment: 6 pages, 6 figures; this version contains an additional appendix not present in the published versio

Nonlinear state estimation using forward-backward propagation of intervals in an algorithm

International audienceThe paper deals with the estimation of the state vector of a discrete-time model from interval output data. When the model outputs are affine in the initial state vector, a number of methods are available to enclose all estimates that are consistent with data by simple sets such as ellipsoids, orthotopes or parallelotopes, thereby providing guaranteed set estimates. In the nonlinear case, the situation is much less developed and there are very few methods that produce such guaranteed estimates. In this paper, the state estimation of a discrete-time model is performed by combining a set-inversion algorithm with a forward-backward propagation of intervals through the model. The resulting methodology is illustrated on an example

Gaussian beam mode analysis of standing waves between two coupled corrugated horns

Abstract—In this paper we present the theoretical analysis of the effects of standing waves between coupled horn antennas that can occur in terahertz quasi-optical systems. In particular we illustrate the approach for the case of two coupled horn antennas as the distance between them is varied. The full mode matching scattering matrix approach is based on combining a standard waveguide mode description of the horn antenna and a quasi-optical Gaussian beam description of the free space propagation. Track is kept of both the backward and forward going components of the propagating fields.We compare theoretical predictions with actual experimental test results for a quasi-optical system operating at a frequency of 0.480 THz

Gaussian beam mode analysis of standing waves between two coupled corrugated horns

Abstract—In this paper we present the theoretical analysis of the effects of standing waves between coupled horn antennas that can occur in terahertz quasi-optical systems. In particular we illustrate the approach for the case of two coupled horn antennas as the distance between them is varied. The full mode matching scattering matrix approach is based on combining a standard waveguide mode description of the horn antenna and a quasi-optical Gaussian beam description of the free space propagation. Track is kept of both the backward and forward going components of the propagating fields.We compare theoretical predictions with actual experimental test results for a quasi-optical system operating at a frequency of 0.480 THz