Extended Data Fig. 4: Probing of the valley polarization via optical polarimetry.
From: Light-wave-controlled Haldane model in monolayer hexagonal boron nitride
Left (red, counter-rotating with the fundamental ω field of the pump) and right (green, co-rotating with the fundamental ω field of the pump) helicities of the third harmonic of a linearly-polarized probe field. The different rows correspond to different intensities of the pump field keeping the ω to 2ω intensity ratio is kept fixed at 2:1 (same as those in Extended Data Fig. 3): a–c, Iω = 2 TW/cm2; d–f, Iω = 4 TW/cm2; g–i, Iω = 6 TW/cm2; j–l, Iω = 8 TW/cm2; m–o, Iω = 10 TW/cm2. The probe polarization is oriented along \(\varGamma -M\). The left column corresponds to the amplitude and interference signals, as discussed in Methods 1.4.2, computed at the frequency point ν = 3ω. The middle column shows the left and right helicity signals computed from the integral of the H3 signal, as measured in the experiment. The right-most column shows the Fourier components of the oscillation in the corresponding middle column panel.
