Abruptly Focusing and Defocusing Needles of Light and Closed-Form Electromagnetic Wavepackets

Fourier optics enforces a tradeoff between length and narrowness in electromagnetic wavepackets, so that a narrow spatial focus diffracts at a large divergence angle, and only infinitely wide beams can remain non-diffracting. We show that it is possible to bypass this tradeoff between the length and narrowness of intensity hotspots, and find a family of electromagnetic wavepackets that abruptly focus to and defocus from high-intensity regions of any aspect ratio. Such features are potentially useful in scenarios where one would like to avoid damaging the surrounding environment, for instance, to target tumors very precisely in cancer treatment, drill holes of very precise dimensions in laser machining, or trigger nonlinear processes in a well-defined region. In the process, we also construct the first closed-form solutions to Maxwell's equations for finite-energy electromagnetic pulses. These pulses also exhibit intriguing physics, with an on-axis intensity peak that always travels at the speed of light despite inherent diffraction

Ultrashort Tilted-Pulse-Front Pulses and Nonparaxial Tilted-Phase-Front Beams

Electromagnetic pulses with tilted pulse fronts are instrumental in enhancing the efficiency of many light-matter interaction processes, with prominent examples including terahertz generation by optical rectification, dielectric laser acceleration, ultrafast electron imaging and X-ray generation from free electron lasers. Here, we find closed-form expressions for tilted-pulse-front pulses that capture their exact propagation dynamics even in deeply nonparaxial and sub-single-cycle regimes. By studying the zero-bandwidth counterparts of these pulses, we further obtain classes of nondiffracting wavepackets whose phase fronts are tilted with respect to the direction of travel of the intensity peak. The intensity profile of these nonparaxial nondiffracting wavepackets move at a constant velocity that can be much greater than or much less than the speed of light, and can even travel backwards relative to the direction of phase front propagation

Quantum Emergence of Linear Particle Accelerator and Anomalous Photon-induced Near-field Electron Microscopy in a Strong Coupling Regime

Photon-induced near-field electron microscopy (PINEM) is a currently developing spectral approach that characterizes quantum electron-light interactions in electron energy gain/loss spectrum, with symmetrically discretized gains or losses of light quanta ($\hbar \omega$), coupled with a laser induced optical near-field. In this letter, we have demonstrated that Linear Particle Accelerator (LPA) and anomalous PINEM (APINEM) can analytically emerge from PINEM-kind interaction in a strong coupling regime, because of quantum interference of spectral photon sidebands overlap. Furthermore, we also found that the quantum interference in point-particle regime with pre-interaction drift can produce interesting optical spectral focusing and a periodically bunching of energy/momentum distribution that enable us to improve the spectral resolution of electron microscopy, imaging and spectroscopy. These observation of LPA and APINEM in strong laser physics can be of great interests for both theoretical and experimental communities, such as ultrafast electron microscopes, attosecond science and laser-driven accelerators

DBLP collective outcome.

(A) Weak ties. (B) Strong ties.</p

Data Description.

<p>Data Description.</p

Number of iterations to inflection point.

<p>(A) Weak ties. (B) Strong ties.</p

Percentage of nodes to inflection point.

<p>(A) Weak ties. (B) Strong ties.</p

The difference (in %) between information reach in strong and weak ties.

The difference (in %) between information reach in strong and weak ties.</p

Percentage of nodes to final spread.

(A) Weak ties. (B) Strong ties.</p

Production functions in critical mass formation.

<p>(A) Decelerating production function. (B) Accelerating production function.</p