Jonathan Nemirovsky

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 beams in photonic crystals

We find accelerating beams in a general periodic optical system, such as photonic crystal slabs, honeycomb lattices, and various metamaterials. These beams retain a shape-preserving profile while bending to highly non-paraxial angles along a circular-like trajectory. The properties of such beams depend on the crystal lattice structure: on a small-scale, the fine features of the beams profile are uniquely derived from the exact structure of the crystalline cells, while on a large-scale the beam only depends on the periodicity of the lattice, asymptotically reaching the free-space analytic solutions when the wavelength is much larger than the cell size. We demonstrate such beams in a 2D Kronig-Penney separable model, but our methodology of finding such solutions is general, predicting accelerating beams in any periodic structure. This highlights how light can be guided through a general system by only tailoring the incoming field, without altering the structure itself.

Experimental generation of arbitrarily shaped diffractionless superoscillatory optical beams

We present, theoretically and experimentally, diffractionless optical beams displaying arbitrarily-shaped sub-diffraction-limited features known as superoscillations. We devise an analytic method to generate such beams and experimentally demonstrate optical superoscillations propagating without changing their intensity distribution for distances as large as 250 Rayleigh lengths. Finally, we find the general conditions on the fraction of power that can be carried by these superoscillations as function of their spatial extent and their Fourier decomposition. Fundamentally, these new type of beams can be utilized to carry sub-wavelength information for very large distances.

Negative radiation pressure and negative effective refractive index via dielectric birefringence

We show that light guided in a planar dielectric slab geometry incorporating a biaxial medium has lossless modes with group and phase velocities in opposite directions. Particles in a vacuum gap inserted into the structure experience negative radiation pressure: the particles are pulled by light rather than pushed by it. This effectively one-dimensional dielectric structure represents a new geometry for achieving negative radiation pressure in a wide range of frequencies with minimal loss. Moreover, this geometry provides a straightforward platform for experimentally resolving the Abrahams-Minkowski dilemma.

Quantum Čerenkov Radiation: Spectral Cutoffs and the Role of Spin and Orbital Angular Momentum

We show that the well-known Cerenkov effect contains new phenomena arising from the quantum nature of charged particles. The Cerenkov transition amplitudes allow coupling between the charged particle and the emitted photon through their orbital angular momentum and spin, by scattering into preferred angles and polarizations. Importantly, the spectral response reveals a discontinuity immediately below a frequency cutoff that can occur in the optical region. Near this cutoff, the intensity of the conventional Cerenkov radiation (CR) is very small but still finite, while our quantum calculation predicts exactly zero intensity above the cutoff. Below that cutoff, with proper shaping of electron beams (ebeams), we predict that the traditional CR angle splits into two distinctive cones of photonic shockwaves. One of the shockwaves can move along a backward cone, otherwise considered impossible for conventional CR in ordinary matter. Our findings are observable for ebeams with realistic parameters, offering new applications including novel quantum optics sources, and opening a new realm for Cerenkov detectors involving the spin and orbital angular momentum of charged particles.

Optimizing 3D multiphoton fluorescence microscopy

We present a new optimization concept for 3D multiphoton fluorescence microscopy by finding the optimal excitation beam giving rise to the smallest possible light-emitting volume or the highest possible signal to noise ratio (SNR).

Light-induced self-synchronizing flow patterns

In this paper, we present the observation of light-induced self- synchronizing flow patterns in a light-fluid system. A light beam induces local flow patterns in a fluid, which oscillate periodically or chaotically in time. The oscillations within different regions of the fluid interact with each other through heat- and surface-tension-induced fluid waves, and they become synchronized. We demonstrate optical control over the state of synchronization and over the temporal correlation between different parts of the flow field. Finally, we provide a model to elucidate these results and we suggest further ideas on light controlling flow and vice versa.

Prolonging the lifetime of relativistic particles by self-accelerating Dirac wavepackets

We show that shaping the wavepackets of Dirac particles can alter fundamental relativistic effects such as length contraction and time dilation. For example, shaping decaying particles as self-accelerating Dirac wavepackets extends their lifetime.

Non-Paraxial Acceleration and Rotation in Curved Surfaces

We present non-paraxial shape-preserving accelerating electromagnetic wavepackets propagating in micro-sized curved surfaces, revealing exotic trajectories and polarization rotation dynamics caused by the interplay of interference effects and the curvature of space.

Cherenkov radiation from electron vortex beams

We find the Cherenkov radiation emitted by vortex electrons, and show that a properly designed photonic waveguide can increase the angular momentum of the electrons. We calculate the selection rules in a relativistic quantum formalism.