  Phase-of-the-phase (PoP) spectroscopy is extended to two-color laser fields
having a circularly counter-rotating polarization. In particular, the higher
harmonics of the (two-color) phase information are analyzed in order to extract
the laser-coherent part of the photoelectron spectra taken under complex target
conditions. We illustrate this with a proof-of-principle simulation by
considering strong-field electron emission from argon atoms within helium
nanodroplets under realistic experimental conditions, i.e., a limited number of
photoemission events. Multiple elastic scattering on neutral helium atoms
creates a laser-incoherent background, but the higher harmonics of the
PoP-signal allow to resolve the coherent contribution to the photoemission.

Atomic Physics;Atomic and Molecular Clusters