Figure 1

Schematic layout of LWFA experiments performed with the spectral phase control of PW laser pulses. The insets (i) and (ii) show the laser spectrum with flattened spectral phase and the temporal profile, respectively, after the feedback compensation of the spectral phase using SRSI and AOPDF. In (i) the measured spectral intensity and the phase are shown in the black and the red lines, respectively. In (ii) the temporal profile from measured spectral phase, shown in the black line, is hardly distinguishable from the transform-limited case shown in the red. The insets (iii) and (iv) show typical electron spectra measured at two positions- one at the end of the magnet and the other at 0.53 meter away.