Fig. 4: Measured instantaneous wavelength for different contrast conditions.

Comparison of the instantaneous wavelengths and reflected laser pulse for the condition with (blue) and without PM (red) and an incoming laser intensity of 10²⁰ W cm⁻² and 2.4 × 10²⁰ W cm⁻², respectively. The solid blue and red lines show the mean value of all shots for each corresponding condition, with the uncertainty, given by the peak-to-valley values, indicated by the shaded areas of the respective color. The dashed blue and red lines indicate the average pulse envelope for each condition normalized to its integral and the dashed black line corresponds to the initial central wavelength.