Fig. 2

Time-integrated FWM using linear polarizations. Time integrated FWM intensity as a function of the time delay at zero field (blue squares) and 10 T (red circles) using linear horizontal polarizations. The dashed green curve corresponds to the instrumental response. The positive time delay corresponds to the pulse sequence shown in Fig. 1c, whereas negative time delay corresponds to the pulse sequence shown in Fig. 1d. The phase conjugate pulse A^* is scanned continuously from negative time delay (arriving at the sample last) to positive time delay (arriving at the sample first). The time delay T between pulses B and C is kept fixed at 0 fs