Fig. 4: Coded Diff-CUP imaging of propagating EMPs in an LN crystal.

a Lossless-encoding CUP setup in the Diff-CUP system. DMD, digital micromirror device; OB, objective lens; SC, streak camera; BS, beamsplitter. b Operation principle of lossless-encoding CUP. The DMD spatially encodes spatiotemporal scenes with a pseudorandom binary pattern by reflecting the incident light to either +12° (+) or –12° (–), creating two beams encoded with complementary patterns. c Quantification of temporal resolution in Diff-CUP. An 800-nm, 50-fs laser pulse (Libra-HE, Coherent) is split by the Mach–Zehnder interferometer into a reference pulse and a signal pulse. The temporal resolution of the system is measured as the minimum, distinguishable temporal distance between the two pulses with a 6 dB contrast-to-noise ratio. d Correlation between each frame and the first frame in the reconstructed movies of EMPs propagating in the LN crystal acquired by conventional CUP and coded Diff-CUP. The correlation curves indicate the phase change induced by the propagating EMPs. Data are presented as mean values ± standard errors of the means (n = 50). e Dependence of the maximum correlation change (\(\triangle\)C/C with C equals to one) in (d) on the number of interferograms used for coded Diff-CUP reconstruction. f Representative snapshots from the reconstructed movie of a 150-ps EMP (launched from left to right) propagating in the LN crystal acquired by coded Diff-CUP (20 interferograms). Shown below are the relative phase changes induced by the EMP obtained by subtracting the first frame from each frame in the movie. Numbers 1–4 denote the four interference fringes in the FOV. Yellow arrows indicate the propagating direction of the EMP. Scale bar, 500 µm. g Spatiotemporal profile of the propagating EMP revealed by processing the interference fringes 1–4 in (f) with the correlation and TM methods. Dashed line indicates the time shift of the EMP peaks. Black arrows denote the pulse width of the EMP.