Breaking symmetry in propagation of radially and azimuthally polarized high power laser pulses in underdense plasma

TL;DR

This paper investigates the instability of high-power azimuthally and radially polarized laser pulses in underdense plasma, demonstrating that plasma channels can suppress filamentation and exploring electron acceleration effects.

Contribution

It reveals the instability mechanisms of polarized laser pulses in plasma and shows how deep plasma channels can eliminate this instability, advancing understanding of laser-plasma interactions.

Findings

Filamentation occurs in uniform plasma with growth rate depending on plasma gradient.

Deep plasma channels suppress the instability.

Electron self-injection and acceleration are achievable with stabilized pulses.

Abstract

Propagation of relativistically intense azimuthally or radially polarized laser pulses (RPP) in underdense plasmas is demonstrated to be unstable, via 3D particle-in-cell simulation and disregarding the Kerr non-linearity. Strong pulse filamentation occurs for RPP in transversely uniform plasma with an increment, $\Gamma$, close to the well-known one depending on acceleration, $\alpha$, and modulated density gradient length, $L$, as $\Gamma \approx (\alpha/L)^{1/2}$. In deep plasma channels the instability vanishes. Electron self-injection and acceleration by the resulting laser pulse wake is explored.