Ultrafast four-wave-mixing spectroscopy with two vacuum fields and coincidence-double-heterodyne detection

In classical macroscopic ultrafast optical four-wave mixing signals, phase matching selects three classes of light-matter interaction pathways: double quantum coherence; non-rephasing; and photon-echo. Multiple pathways contribute to each of these signals. We show that a coincidence-double-heterodyne detection scheme that employs two classical and two vacuum fields can isolate a single pathway contribution to each of these signals. We further demonstrate the advantage of the proposed technique by comparing it with the classical photon-echo signal for a model Frenkel-exciton dimer. (c) 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement