arXiv subjects

Omar Boughdad

Publications and source records attributed to Omar Boughdad.

3 recordsLinked to original sources

arXiv2020

Experimental observation of turbulent coherent structures in a superfluid of light

We experimentally explore the rich variety of nonlinear coherent structures arising in a turbulent flow of superfluid light past an obstacle in an all-optical configuration. The different hydrodynamic regimes observed are organised in a unique phase diagram involving the velocity of the flow and the diameter of the obstacle. Then, we focus on the vortices nucleated in the wake of the obstacle by investigating their intensity profile and the dependence of the radius of their core on the healing length. Our results pave the way for further investigations on turbulence in photon superfluids and provide versatile experimental tools for simulating quantum transport with nonlinear light.

physics.optics↗

arXiv2019

Anisotropic nonlinear refractive index measurement of a photorefractive crystal via spatial self-phase modulation

We show that the refractive index modification photoinduced in a biased nonlinear photorefractive crystal can be accurately measured and controlled by means of a background incoherent illumination and an external electric field. The proposed easy-to-implement method is based on the far-field measurement of the diffraction patterns of a laser beam propagating through a self-defocusing medium undergoing spatial self-phase modulation. For various experimental conditions, both saturation intensity and maximum refractive index modification have been measured. We also clearly evidence and characterise the anisotropic nonlinear response of the crystal in the stationary regime.

physics.optics↗

arXiv2018

Superfluid motion and drag-force cancellation in a fluid of light

Quantum fluids of light merge many-body physics and nonlinear optics, through the study of light propagation in a nonlinear medium under the shine of quantum hydrodynamics. One of the most outstanding evidence of light behaving as an interacting fluid is its ability to carry itself as a superfluid. Here, we report a direct experimental detection of the transition to superfluidity in the flow of a fluid of light past an obstacle in a bulk nonlinear crystal. In this cavityless all- optical system, we extract a direct optical analog of the drag force exerted by the fluid of light and measure the associated displacement of the obstacle. Both quantities drop to zero in the superfluid regime characterized by a suppression of long-range radiation from the obstacle. The experimental capability to shape both the flow and the potential landscape paves the way for simulation of quantum transport in complex systems.

physics.optics↗