Extended Data Fig. 1: Measurement of arbitrary amplitude and phase responses by free-electron homodyne detection.
From: Attosecond electron microscopy by free-electron homodyne detection
Periodic excitations of an investigated sample resulting in modulations of the amplitude and/or phase of the probing electron wavefunction at harmonic frequencies ω, 2ω, 3ω, … of the exciting optical carrier frequency. These modulations can be probed by the analysis of spectrally symmetric (a-f) and antisymmetric (d-l) signal channels in FREHD. PINEM-type phase modulation leads to conjugate symmetric and amplitude modulation to symmetric kinetic energy sidebands in the Wigner function (first column). Reference interaction with a pure phase modulation (that is, convolution with a conjugate symmetric Wigner function; second column) yields either symmetric (b) or antisymmetric (h, k) spectrograms for non-dispersed electron wave packets. These spectrograms are evaluated using virtual homodyne detection of the spectral sidebands P−1 and P1, yielding a phase-dependent signal characteristic for the initial interaction type (third column). Simulation parameters: g = 0.2, a = 0.2, gref = 0.5, λ = 800 nm optical wavelength, E0 = 120 keV electron kinetic energy, t = 200 ps propagation time.
