Polarization Flipping of Even-Order Harmonics in Monolayer Transition-Metal Dichalcogenides
(a) MIR-polarization-angle dependence of WS2 measured by rotating the MIR polarization angle . (b) HHG polarization angle resolved for multiple harmonics as a function of . The odd harmonics are aligned along the MIR field all the time, whereas the polarization of the even-order harmonics is fixed along the direction of the mirror planes. (c, d) The same measurements for MoSe2. The HHG polarization angle exhibits complex behavior both for the odd- and even-order harmonics.