Deflection of a reflected intense circularly polarized light beam induced by asymmetric radiation pressure

TL;DR

This paper reveals a new deflection effect of intense circularly polarized laser beams caused by asymmetric radiation pressure, leading to out-of-plane deviation, confirmed by theoretical modeling and 3D simulations.

Contribution

It introduces a novel theoretical model and simulation results demonstrating laser beam deflection due to spin angular momentum in relativistic plasma interactions.

Findings

Deflection angles up to several milliradians observed.

Deflection depends on laser pulse and plasma parameters.

Confirmed by 3D particle-in-cell simulations.

Abstract

A novel deflection effect of an intense laser beam with spin angular momentum is revealed theoretically by an analytical modeling using radiation pressure and momentum balance of laser plasma interaction in the relativistic regime, as a deviation from the law of reflection. The reflected beam deflects out of the plane of incidence with a deflection angle up to several milliradians, when a non-linear polarized laser, with the intensity $I_0\sim10^{19}$W/cm$^2$ and duration around tens of femtoseconds, is obliquely incident and reflected by an overdense plasma target. This effect originates from the asymmetric radiation pressure caused by spin angular momentum of the laser photons. The dependence of the deflection angle of a Gaussian-type laser on the parameters of laser pulse and plasma foil is theoretically derived, which is also confirmed by three dimensional particle-in-cell simulations of circularly polarized laser beams with the different intensity and pulse duration.