  Momentum-resolved photoelectron emission from xenon in colinearly polarized
two-color laser fields at above-threshold ionization conditions is studied both
experimentally and theoretically. We utilize phase-of-the-phase spectroscopy as
recently introduced by Skruszewicz et al., Phys. Rev. Lett. 115, 043001 (2015)
to analyze the dependence of the yields on the relative phase $\varphi$ between
the fundamental and second harmonic laser fields. The resulting phase-of-phase
spectra feature a characteristic checkerboard pattern, which can analytically
be described within the strong-field approximation.
