Controlling photoelectron interference along the quantization axis of multiphoton ionization in circularly polarized fields

We measure angle- and phase-resolved photoelectron momentum distributions of multiphoton ionization of xenon atoms using bicircular laser fields. In our experiment, the continuum electron ring currents with larger orbital angular momentum are prepared by an intense circular polarized laser field at 400 nm and probed with a spatiotemporally overlapped corotating or counter-rotating weak 800 nm laser pulse. Interestingly, a distinct “carpetlike” interference pattern in the direction of laser propagation is observed for the counter-rotating fields, but not for the corotating fields. By analyzing the momentum-resolved photoelectron yield oscillations with respect to the two-color relative phase (phase-of-the-phase spectrum), we observe a distinct angular dependence in the phase-of-the-phase spectrum in the laser propagation plane when the fields are counter-rotating. In contrast, in the corotating geometry, the phase-of-the-phase spectrum in the laser propagation plane displays an isotropic phase profile. We explain that the carpetlike interference in the propagation plane arises from the constructive and destructive interference of the continuum electron ring currents with different magnetic quantum number, which can be controlled by the light helicity.