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

## TL;DR

This paper derives exact analytical expressions for ultrashort tilted-pulse-front pulses and nondiffracting wavepackets, revealing their complex propagation dynamics and phase front behavior in nonparaxial regimes, with implications for advanced light-matter interaction applications.

## Contribution

It provides closed-form solutions for nonparaxial tilted-pulse-front pulses and introduces classes of nondiffracting wavepackets with tilted phase fronts, expanding understanding of their propagation characteristics.

## Key findings

- Exact propagation dynamics in nonparaxial regimes
- Nondiffracting wavepackets with tilted phase fronts
- Wavepackets traveling at superluminal or backward speeds

## Abstract

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.

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Source: https://tomesphere.com/paper/1903.00824