Bragg Scattering of Light in Vacuum Structured by Strong Periodic Fields

Elastic scattering of laser radiation due to vacuum polarization by spatially modulated strong electromagnetic fields is considered. The Bragg interference arising at a specific impinging direction of the probe wave concentrates the scattered light in specular directions. The interference maxima are enhanced with respect to the usual vacuum polarization effect proportional to the square of the number of modulation periods within the interaction region. The Bragg scattering can be employed to detect the vacuum polarization effect in a setup of multiple crossed superstrong laser beams with parameters envisaged in the future Extreme Light Infrastructure.

Figure 1

(a) The Feynman diagram describing the photon scattering in a strong external electromagnetic field. (b) Bragg scattering of a probe laser beam by a set of focused strong laser beams.

Figure 2

The dependence of the scattering probability on the probe impinging angle [the factor $\mathcal{W}(\theta )$]: (solid line) $B$-field case, the upper curve—transverse polarization, the lower curve—longitudinal polarization; (dashed line) $E$-field case, the upper curve—longitudinal polarization, the lower curve—transverse polarization.