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Schlagwörter:
nonlinear optics, photovoltaic effect
Zusammenfassung:
Light-induced electron dynamics in monolayer hexagonal boron nitride is theoretically investigated under the influence of two-color linearly-polarized laser fields at frequencies ω and 2ω, by solving the time-dependent Schrödinger equation with a tight-binding model. In the weak field regime, it is confirm that the injection of ballistic current arises from the breakdown of time-reversal symmetry. This phenomenon is attributed to quantum interference between two distinct excitation paths: a one-photon (2ℏω) absorption path and a two-photon (ℏω) absorption path. In a strong field regime, the analysis reveals that the two-color laser fields may generate a substantial population imbalance within momentum space, consequently facilitating the injection of ballistic current even in a deeply off-resonant regime. The findings demonstrate that a pronounced population imbalance exceeding 30% of excited electrons can be realized without relying on the ellipticity of the fields. This highlights the potential of linearly polarized light for efficient photovoltaic effects and valley population control in 2D systems and heterostructures.
