Energy shedding during nonlinear self-focusing of optical beams

Travis, Christopher; Norris, Greg; McConnell, Gail; Oppo, Gian-Luca

doi:10.1364/oe.21.023459

Cited by 3 publications

(2 citation statements)

References 13 publications

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“…For the case of spatio-temporal pulsed input we present results of the effects of the sign and magnitude of group velocity dispersion of the medium. We also describe the energy shedding that takes place during the self-focusing processes as the beam reshapes on entry to the medium and on propagation to a stable solitonic profile [3].…”

Section: Simulation Resultsmentioning

confidence: 99%

Self-focusing of Optical Beams Below the Diffraction Limit

et al. 2014

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Section: Simulation Resultsmentioning

confidence: 99%

Self-focusing of Optical Beams Below the Diffraction Limit

et al. 2014

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“…One especially relevant observation is the appearance of an annular structure around the main core of the self-trapped beam. In a recent study [11], it was shown that high-power self-trapped beams can shed energy away due to long-lived oscillations in amplitude and width, caused by periodic focusing and defocusing. This could explain the formation of the ring structure we observe in our experiments.…”

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Steering and guiding light with light in a nanosuspension

2013

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We experimentally demonstrate guiding of a low-power probe beam (633 nm wavelength) by means of a lightinduced waveguide generated by the self-focusing of a strong pump beam (532 nm wavelength) in an artificial nonlinear medium, constituted by a colloidal suspension of dielectric nanoparticles. We also demonstrate optical steering of the probe beam by controlling the direction of propagation of the pump beam. The distance over which guiding is demonstrated (5 mm . Qualitatively, the nonlinearity can be understood as a consequence of the existence of an optical gradient force, which attracts (repels) nanoparticles to (from) the regions of highest optical intensity when their refractive index (n p ) is higher (lower) than that of the surrounding medium (n m ). This leads to spatial variations of the effective refractive index directly related with the intensity distribution of the incident beam. Although the phenomenon was initially described in terms of a pure Kerr nonlinearity [4], it was recognized later that this assumption is an oversimplification. In fact, it is well known that a Kerr nonlinearity does not yield stable soliton propagation in the 2 1D case [5]. This fact renewed the interest on the subject and motivated the development of several theoretical models intended to elucidate the right kind of nonlinearity produced by the nanosuspensions. The general idea is to consider the medium as a gas of particles [6][7][8][9], where diffusion is driven by the optical gradient force until reaching equilibrium conditions. This leads to diverse expressions for the position-dependent particle density ρr, determined by the incident light spatial distribution and the characteristics of the nonlinear response of the medium.In the slowly varying envelope approximation, the propagation of a light beam in the medium is described bywhere the optical field is given by Er; t ψr exp ik 0 n b z − ωt, with k 0 being the wavenumber of the light in vacuum, ω its frequency, and n b the refractive index of the medium in absence of light. Fρ represents a complex function of the particle density (or concentration), whose real and imaginary parts are associated with the refractive index and Rayleigh scattering loss, respectively. The equation describing the interaction between the incident light and the medium, which is specified for each theoretical model, forms a coupled system with Eq.(1). In order to explain the observation of stable propagation of OSS in 2 1D, different considerations and assumptions have been made, including for example, the presence of nonlinear Rayleigh losses [7], hard-sphere potential interactions [8], or screened Coulomb repulsions ("van der Waals" gas) [9], which lead to different kinds of nonlinearities, from Kerr to exponential. With the aim of testing the different theoretical approaches, new experiments were conducted recently [10].In this Letter, we present experimental results on the guiding of a weak probe beam (wavelength λ r 633 nm) by means of the waveguide induced by an intense pump beam (wav...

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Random medium model for cusping of plane waves

Korotkova

2017

Opt. Lett.

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We introduce a model for a three-dimensional (3D) Schell-type stationary medium whose degree of potential's correlation satisfies the Fractional Multi-Gaussian (FMG) function. Compared with the scattered profile produced by the Gaussian Schell-model (GSM) medium, the Fractional Multi-Gaussian Schell-model (FMGSM) medium gives rise to a sharp concave intensity apex in the scattered field. This implies that the FMGSM medium also accounts for a larger than Gaussian's power in the bucket (PIB) in the forward scattering direction, hence being a better candidate than the GSM medium for generating highly-focused (cusp-like) scattered profiles in the far zone. Compared to other mathematical models for the medium's correlation function which can produce similar cusped scattered profiles the FMG function offers unprecedented tractability being the weighted superposition of Gaussian functions. Our results provide useful applications to energy counter problems and particle manipulation by weakly scattered fields.

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Energy shedding during nonlinear self-focusing of optical beams

Cited by 3 publications

References 13 publications

Self-focusing of Optical Beams Below the Diffraction Limit

Self-focusing of Optical Beams Below the Diffraction Limit

Steering and guiding light with light in a nanosuspension

Random medium model for cusping of plane waves

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