Rivka Bekenstein

Nondiffracting Accelerating Wave Packets of Maxwell's Equations

We present the spatially accelerating solutions of the Maxwell equations. Such beams accelerate along a circular trajectory extending beyond the paraxial regime, thus generalizing the concept of accelerating Airy beams.

Self-accelerating optical beams in highly nonlocal nonlinear media

We find self-accelerating beams in highly nonlocal nonlinear optical media, and show that their propagation dynamics is strongly affected by boundary conditions. Specifically for the thermal optical nonlinearity, the boundary conditions have a strong impact on the beam trajectory: they can increase the acceleration during propagation, or even cause beam bending in a direction opposite to the initial trajectory. Under strong self-focusing, the accelerating beam decomposes into a localized self-trapped beam propagating on an oscillatory trajectory and a second beam which accelerates in a different direction. We augment this study by investigating the effects caused by a finite aperture and by a nonlinear range of a finite extent.

Loss-proof self-accelerating beams and their use in non-paraxial manipulation of particles’ trajectories

Self-accelerating beams--shape-preserving bending beams--are attracting great interest, offering applications in many areas such as particle micromanipulation, microscopy, induction of plasma channels, surface plasmons, laser machining, nonlinear frequency conversion and electron beams. Most of these applications involve light-matter interactions, hence their propagation range is limited by absorption. We propose loss-proof accelerating beams that overcome linear and nonlinear losses. These beams, as analytic solutions of Maxwells equations with losses, propagate in absorbing media while maintaining their peak intensity. While the power such beams carry decays during propagation, the peak intensity and the structure of their main lobe region are maintained over large distances. We use these beams for manipulation of particles in fluids, steering the particles to steeper angles than ever demonstrated. Such beams offer many additional applications, such as loss-proof self-bending plasmons. In transparent media these beams show exponential intensity growth, which facilitates other novel applications in micromanipulation and ignition of nonlinear processes.

Wavefront shaping through emulated curved space in waveguide settings

The past decade has witnessed remarkable progress in wavefront shaping, including shaping of beams in free space, of plasmonic wavepackets and of electronic wavefunctions. In all of these, the wavefront shaping was achieved by external means such as masks, gratings and reflection from metasurfaces. Here, we propose wavefront shaping by exploiting general relativity (GR) effects in waveguide settings. We demonstrate beam shaping within dielectric slab samples with predesigned refractive index varying so as to create curved space environment for light. We use this technique to construct very narrow non-diffracting beams and shape-invariant beams accelerating on arbitrary trajectories. Importantly, the beam transformations occur within a mere distance of 40 wavelengths, suggesting that GR can inspire any wavefront shaping in highly tight waveguide settings. In such settings, we demonstrate Einsteins Rings: a phenomenon dating back to 1936.

Observation of Accelerating Wave Packets in Curved Space

We present the first experimental observation of accelerating beams in curved space. More specifically, we demonstrate, experimentally and theoretically, shape-preserving accelerating beams propagating on spherical surfaces: closed-form solutions of the wave equation manifesting nongeodesic self-similar evolution. Unlike accelerating beams in flat space, these wave packets change their acceleration trajectory due to the interplay between interference effects and the space curvature, and they focus and defocus periodically due to the spatial curvature of the medium in which they propagate.

Induction of topological transport by long ranged nonlinearity

We present topologically-protected transport in systems that are topologically trivial, but a long-range nonlinearity induces unidirectional transport and topological immunity to scattering from defects.

Curved space nanophotonics inspired by general relativity

We present nanophotonic structures in three dimensions inspired by General Relativity concepts, enabling control over the light dynamics: the group and phase velocities together with the spatial modes structure, suggesting implications to enhancing light-matter interaction.

Microparticles manipulation by nonparaxial accelerating beams

We introduce loss-proof shape-invariant nonparaxial accelerating beams that overcome both diffraction and absorption, and demonstrate their use in acceleration of microparticles inside liquids along curved trajectories that are significantly steeper than ever achieved.

Loss-proof self-accelerating plasmons and exponentially growing beams

We introduce a new class of 1 & 2-dimensional beams that overcome both diffraction & absorption, enabling accelerating plasmons that maintain their intensity profile. In free space these beams exhibit a counterintuitive exponential intensity growth.

Photonic topological dynamics induced by curved surfaces

We present topological photonics in curved space. We use 1D waveguide lattices on curved surfaces, and show that the curvature of the surface induces topological phase transfer dynamics, Thouless pumping, localization and delocalization of waves.