Figure 2.

Experimental demonstration of transverse optical modulation of free electrons via arbitrarily shaped ultrafast light fields. (a–c) Phase patterns implemented on the SLM used to modulate the light field: (a) homogeneous phase distribution, (b) π-phase shift along the horizontal direction, and (c) π-phase shift along the vertical direction. (d–f) Light transverse profiles measured for the corresponding SLM phase patterns in (a)–(c): a Gaussian profile in (d), a two-lobed horizontal Hermite-Gaussian profile (HG₁₀) in (e), and a two-lobed vertical Hermite-Gaussian profile (HG₀₁) in (f). (g–j) Inelastically scattered electron spatial maps measured under optical illumination with (g) Gaussian and (h–j) Hermite-Gaussian beams, obtained by the SLM modulation of the ultrafast light pulses shown in (a)–(c). All images are taken when the electron and light wavepackets have maximum temporal overlap.