Attosecond Temporal Gating with Elliptically Polarized Light

Temporal gating allows high accuracy time-resolved measurements of a broad range of ultrafast processes. By manipulating the interaction between an atom and an intense laser field, we extend gating into the nonlinear medium in which attosecond optical and electron pulses are generated. Our gate is an amplitude gate induced by ellipticity of the fundamental pulse. The gate modulates the spectrum of the high harmonic emission and we use the measured modulation to characterize the sub-laser-cycle dynamics of the recollision electron wave packet.

Figure 1

(a) Schematic description of the electron wave packet’s lateral shift induced by ellipticity for three typical short electron trajectories. (b) Experimentally measured ellipticity response for Ne atoms. Presented are the harmonics yield as a function of the laser ellipticity, normalized to the signal measured with $ϵ=0$.

Figure 2

Reconstruction of the harmonics time of emission. (a) Initial velocity ${\tilde{V}}_i(N\omega )$ calculated by Eq. (6) using the experimental response, presented in Fig. 1b. The experimental measurement and associated errors are presented for the following: $ϵ=0.11$ (cyan circles), $ϵ=0.14$ (green circles), $ϵ=-0.11$ (red circles), and $ϵ=-0.14$ (blue circles). An average response is represented by the black line. (b) Calculated initial velocity $V_i(t)/V(t_{\max })$. (c) Reconstruction of the time of emission for each harmonic number (blue circle) together with the theoretical curve (line). The arrow indicates that we fixed the time of emission of the 29th harmonic.