Assaf Barak

Random-phase surface-wave solitons in nonlocal nonlinear media

We demonstrate, theoretically and experimentally, incoherent surface solitons in a noninstantaneous nonlocal nonlinear media. These incoherent surface waves are located at the interface between a nonlinear medium with long-range nonlocality and a linear dielectric medium (air).

Multisoliton ejection from an amplifying potential trap

We study theoretically the dynamics of a beam launched inside an amplifying trap potential. Raising the amplification transforms the dynamics from linear tunneling at low amplification to periodic ejection of a sequence of identical solitons (when the amplification rate exceeds the tunneling rate) and, at strong amplification, to nonperiodic multisoliton ejection.

Complex Nonlinear Opto-Fluidity

We demonstrate symbiotic dynamics of light and nano-particles suspended in liquid. Light-force varies the local particle density, modifies the fluid properties (surface-tension, viscosity), inducing motion/rotation in the fluid, causing synergetic nonlinear-dynamics of light and fluid.

Autoresonant propagation of incoherent light-waves

We study, theoretically and experimentally, the evolution of optical waves with randomly-fluctuating phases in a spatially chirped nonlinear directional coupler. As the system crosses its linear resonance, we observe collective self-phase-locking (autoresonance) of all mutually-incoherent waves, each with its own pump, and simultaneous amplification until the pumps are exhausted. We show that the autoresonant transition in this system exhibits a sharp threshold, common to all mutually-incoherent waves comprising the light beam.

Complex nonlinear opto-fluidics: Controlling flow with light and vice-versa

We demonstrate symbiotic dynamics of light and nano-particles suspended in liquid. Light-force varies the local particle density, modifies the fluid properties (surface-tension, viscosity), inducing flow patterns in the fluid, causing synergetic nonlinear-dynamics of light and fluid.

Optical control of surface-tension effects in complex nanofluids

We study coupling between light and nano-particle suspensions, through surface-tension effects in capillaries. Increasing light intensity far-away from the interface causes huge changes in the fluid level, manifesting optical control over mechanical properties of fluids.

Observation of soliton tunneling phenomena and soliton emission

We study, theoretically and experimentally, nonlinear dynamics of a wavepacket launched inside a potential well. Increasing the power of the wavepacket transforms its dynamics from linear tunneling, to soliton tunneling, and eventually to soliton emission.

Random-Phase Surface-Wave Solitons in Nonlocal Nonlinear Media

We demonstrate, theoretically and experimentally, random-phase (incoherent) surface-wave solitons localized at the boundary between a dielectric medium (air) and a nonlinear material with a large range of nonlocality.