Fig. 5: Experimental demonstration of field retrieval using the PENGUIN technique in comparison with the IFROG method for n = 2.

a Measured (top) and retrieved (bottom) balanced IFROG spectrograms (s = 1). b Representative measured (dark blue) and retrieved (orange) IAC traces for various balance factors s using the PENGUIN technique. c Retrieved fields in the frequency domain for the IFROG measurement (red) and a series of PENGUIN measurements (green). Magnitudes are shown as solid lines and phases as dotted lines. The green bands bound nine separate measurements with balance factors between s = 0.21 and s = 0.84 (see text). The independently measured fundamental spectral magnitude is shown in gray for reference. d Time-domain representation of the retrieved fields in c showing the intensity envelopes (solid lines) and temporal phases (dotted lines) with the linear component (ω₀t) removed. The FWHM duration of the intensity envelope is around 6.4 fs for both retrieval methods