Figure 2.

Spatial arrangement of the pump pulse (black) and the two probe pulses. The probe pulse 1 (blue) is polarized along the y axis, the probe pulse 2 (red) is polarized along the z axis. Polarization direction of the pump pulse is switched between y and z axis. Yellow box: Polarization directions (gray arrows) of the probe beams (blue and red dots) and of the pump beam (black dot) in the plane of the sample; red and blue arrows indicate the projections of the probe beams as they approach the pump beam overlapping in the sample volume.