Search results for "Wave mixing"
showing 10 items of 107 documents
Absolute instability in backward wave four-wave mixing: spatial effects
2010
The spatial distribution of new beams generated above the threshold of absolute instability of two counterpropagating incoherent light waves is studied and compared with the results of calculation.
Four-wave mixing instabilities in telecom fibers
2012
Instabilities in fiber four-wave mixing are investigated, revealing the formation of colliding dispersive shock waves in the normal GVD regime and collective modulation instabilities in the anomalous GVD regime.
160-GHz picosecond pulse train generation through multiwave mixing compression of a dual frequency beat signal
2002
We report the experimental generation and characterization of a 160-GHz picosecond puise train using multiple four-wave mixing temporal compression of an initial dual frequency beat signal in the anomalous-dispersion regime of a non-zero dispersion shifted fiber.
Impact of fourth-order dispersion in the modulational instability spectra of wave propagation in glass fibers with saturable nonlinearity
2010
We analyze the modulational instability (MI) of light waves in glass fibers with a local saturable nonlinear refractive index. We identify and discuss the salient features of the effect of the fourth order of the fiber dispersion, in the MI spectra. Particularly, we find that in fibers with negative sign of the second-order dispersion and positive sign of the fourth-order dispersion (FOD), the two existing types of MI processes, called processes of type I, which generate a single pair of sidebands, and processes of type II, which lead to two pairs of sidebands, become highly sensitive to the magnitude of the FOD, both quantitatively and qualitatively. We demonstrate the existence of a criti…
<title>Phase conjugation properties of a-As-S-Se films</title>
2006
Light wavefront inversion (phase conjugation) in a-As-S-Se films has been studied experimentally. Phase conjugation (PC) of plane and spherical waves is carried out in a-As40S15Se45 films using degenerate four-wave-mixing (DFWM) geometry at 633 nm. In the plane wave case simultaneous PC efficiency and DE measurements have been made versus exposure time, light intensity and holographic grating period. The maximal PC efficiency was 2.3% and the minimal PC specific recording energy was 2 J/(cm2%) whereas the maximal DE was 0.9% and the minimal specific hologram recording energy was 10 J/(cm2%). The optimal grating period was 2 μm. When compared to a-Se films a-As-S-Se films exhibit lower PC ef…
Four-wave mixing control in the filamentation of ultrafast Bessel beams via longitudinal intensity-shaping
2017
International audience; Bessel beams exploit conical energy flow to yield near-uniform intensity along a line focus which has been shown to be extremely attractive for laser processing in dielectrics. At high power, however, the nonlinear Kerr effect is known to induce significant oscillations of the on-axis intensity which is deleterious for machining applications. Here, we show through theory and numerical modelling how this problem can be understood and overcome by appropriate spatial phase shaping of the input profile. Our results also solve the longstanding problem related to the nonlinear Bessel beam dynamics seen at an air-dielectric interface.
Nonlinear Multimode Fiber Optics
2018
We overview recent advances in the nonlinear optics of multimode optical fibers, including ultrabroadband sideband and supercontinuum generation, Kerr and Raman beam cleanup, modal modulation instabilities, four wave mixing, and second harmonic beam cleaning.
Nonlinear parametric resonances in quasiperiodic dispersion oscillating fibers
2015
We numerically study the evolution of the spectrum of parametric resonance or modulation instability sidebands in quasiperiodic dispersion oscillating fibers. We separately consider a linear variation along the fiber of either the spatial period, the average dispersion, or the amplitude of the dispersion oscillation. We found that this linear variation of the dispersion oscillating fiber parameters may provide different novel mechanisms for the splitting of the resonance sideband spectrum, owing to coherent interference between quasi-resonant waves that are generated at different points along the fiber. (C) 2015 Elsevier B.V. All rights reserved.
Toward a thermodynamic description of supercontinuum generation
2008
International audience; We consider the incoherent nonlinear regime of the supercontinuum generation process in optical fibers. We show that, under certain conditions, the phenomenon of spectral broadening inherent to the supercontinuum generation may be described by simple thermodynamic arguments based on the kinetic wave theory. Accordingly, the supercontinuum generation process may be regarded as a thermalization process, which is characterized by an irreversible evolution of the optical field toward a thermodynamic equilibrium state, i.e., the state of maximum nonequilibrium entropy.
Control of nonlinear instabilities in Bessel beams using shaped longitudinal intensity profiles
2017
International audience; We show that tailored longitudinal intensity shaping of a non-diffracting Bessel beam can strongly reduce four wave mixing induced oscillations and stabilize nonlinear propagation at ablation-level intensities