Fig. 3: Characterizing an ST meron whose polarization distribution is imprinted on a two-sheet paraboloid spectral surface.
From: Ultrafast space-time optical merons in momentum-energy space
a Measured (top row) and calculated (bottom row) spectral Stokes parameters s(kx, ky) in (kx, ky)-space (integrated over all temporal frequencies ω). b A plot of the Stokes vector distribution (arrows) reconstructed from the measurements in (a), overlaid with the measured spectral intensity profile I(kx, ky) measurements (colormap). c Cross-sectional plots of b at different iso-frequency planes corresponding to λ = 795.95, 795.8, and 795.65 nm. d Measured Stokes vector n(kx, ky, λ) (arrows) plotted in the 3D spatiotemporal spectral domain (momentum-energy space), plotted over the ST spectral surface overlaid with the measured spectral intensity profile I(kx, ky). e Spatiotemporal Stokes parameters (s0, s1, s2, s3) at a fixed axial plane z = 0, where s0 corresponds to the total intensity. The panels are plotted in the (x, τ) plane corresponding to y = 0. The first row presents the measurements and the second row the corresponding theoretical predictions. In d the measured temporal bandwidth is Δλ ≈0.8 nm, and the spatial bandwidth is Δkr ≈0.18 rad/mm; in e the measured pulse width at the beam center is Δτ ≈6 ps, and the beam size at the pulse center is Δx ≈56 μm.
