Search results for "Kerr"

Spacetime Foam Model of the Schwarzschild Horizon

2003

We consider a spacetime foam model of the Schwarzschild horizon, where the horizon consists of Planck size black holes. According to our model the entropy of the Schwarzschild black hole is proportional to the area of its event horizon. It is possible to express geometrical arguments to the effect that the constant of proportionality is, in natural units, equal to one quarter.

Solitons in Optical Fibers

1996

In the near future nonlinear optics should probably revolutionize the world of telecommunications and computer technologies. With lasers producing highintensity and short-duration optical pulses, it is now possible to probe the interesting, and potentially useful, nonlinear effects in optical systems and waveguides. Among the guiding structures, the optical fiber is an interesting (Gloge 1979) and important device (Mollenauer and Stolen 1982; Doran and Blow 1983). In an optical transmission system using linear pulses, the bit rate of transmission is limited by the dispersive character of the material, which causes the pulse to spread out an eventually overlap to such an extend that all the …

Incoherent solitons generated in instantaneous response nonlinear Kerr media

2004

We show theoretically and experimentally in an optical fiber system, that incoherent domain wall solitons can be generated spontaneously from incoherent light, despite of the instantaneous response of the fiber Kerr nonlinearity.

Cross-Kerr nonlinearity in optomechanical systems

2015

We consider the response of a nanomechanical resonator interacting with an electromagnetic cavity via a radiation pressure coupling and a cross-Kerr coupling. Using a mean field approach we solve the dynamics of the system, and show the different corrections coming from the radiation pressure and the cross-Kerr effect to the usually considered linearized dynamics.

High-field quantum calculation reveals time-dependent negative Kerr contribution

2013

The exact quantum time-dependent optical response of hydrogen under strong field near infrared excitation is investigated and compared to the perturbative model widely used for describing the effective atomic polarization induced by intense laser fields. By solving the full 3D time-dependent Schr\"{o}dinger equation, we exhibit a supplementary, quasi-instantaneous defocusing contribution missing in the weak-field model of polarization. We show that this effect is far from being negligible in particular when closures of ionization channels occur and stems from the interaction of electrons with their parent ions. It provides an interpretation to higher-order Kerr effect recently observed in v…

An intrinsic characterization of the Kerr metric

2009

We give the necessary and sufficient (local) conditions for a metric tensor to be the Kerr solution. These conditions exclusively involve explicit concomitants of the Riemann tensor.

Analytical investigation of solitary waves in nonlinear Kerr medium

2004

Abstract We study analytically the solution of nonlinear equation which result from the propagation of electromagnetic waves within a nonlinear Kerr medium. The medium is characterized by a dielectric constant which varies periodically and depends on the local field intensity. As a first step, we detail the resolution of the nonlinear equations with a quadratic nonlinearity. After that, we apply the slowly varying envelope approximation to obtain a Sine–Gordon equation. In this kind of nonlinearity, a gap solitons occurs. Moreover we verify that the solutions of the nonlinear equation for all frequencies within the gap are solitons solutions. After that we study the conditions of apparition…

Kerr and Faraday Rotations of Magneto-Optical Multilayers under the Condition of Total Internal Reflection

1999

Adaptive Kerr-Assisted Transverse Mode Selection in Multimode Fibers

2019

Multimode optical fibers (MMFs) have recently regained interest because of the degrees of freedom associated with their different eigenmodes. In the nonlinear propagation regime in particular, new phenomena have been unveiled in graded-index (GRIN) MMFs such as geometric parametric instabilities and Kerr beam self-cleaning [1, 2]. The speckled pattern observed at the output of the MMF at low powers, is transformed at high powers into a bell-shaped beam close to the fundamental mode. Recent work has also demonstrated that Kerr beam self-cleaning can lead to a low-order spatial mode, different from a bell-shape, by adjusting the laser beam in-coupling conditions [3]. An attractive way to syst…

Analysis of femtosecond Raman-induced polarization spectroscopy (RIPS) in N2 and CO2 by fitting and scaling laws

2000

Raman-induced polarization spectroscopy (RIPS) experiments were conducted at room temperature and pressures below 2 atm in pure N2 and CO2. Both homodyne and optically heterodyne detection were used. Calculations of the signal as a function of the pump–probe delay were performed taking into account the pulse duration of the laser, the rotational dependence of the dephasing rates and the small instantaneous electronic Kerr effect. The observed decay and shape of the rotational quantum beats are in good agreement with the calculations. Several sets of linewidth coefficients corresponding to the diagonal part of the collisional–rotational relaxation matrix were used. This matrix was choosen am…