Carrier-envelope-phase control of asymmetries in the multiphoton ionization of xenon atoms by ultrashort bichromatic fields

摘要

We report on bichromatic multiphoton ionization of xenon atoms (Xe) to demonstrate carrier-envelope-phase (CEP) control of lateral asymmetries in the photoelectron momentum distribution. In the experiments, we employ a 4f polarization pulse shaper to sculpture bichromatic fields with commensurable center frequencies ω_1 : ω_2 = 7 : 8 from an over-octave-spanning CEP-stable white light supercontinuum by spectral amplitude and phase modulation. The bichromatic fields are spectrally tailored to induce controlled interferences of 7- vs 8-photon quantum pathways in the 5P_(3/2) ionization continuum of Xe. TheCEP sensitivity of the asymmetric final-statewave function arises from coherent superposition of continuum states with opposite parity. Our results demonstrate that shaper-generated bichromatic fieldswith tailored center frequency ratio are a suitable tool to localizeCEP-sensitive asymmetries in a specific photoelectron kinetic-energy window.