using terahertz emission spectroscopy*

As a Dirac semimetal, PtSe₂ has attracted increasing attention due to its interesting fundamental physics and potential application for photonics. In this work, THz generation from PtSe₂ thin films under linear- and circular-polarized infrared femtosecond laser excitation at room temperature is systematically studied. By changing the polarization and helicity of the pump pulses, the THz emission mechanism is confirmed to be a combination of linear and circular photon drag effects, which is consistent with the mechanisms of linear injection current and circular shift current, both of which arise from photon-induced electron transitions in PtSe₂. We also demonstrate the ability to control the polarization of the emitted THz radiation by tuning the pump laser. Our observations provide further insights into the nonlinear optical phenomena in PtSe₂ and new perspectives on the application of PtSe₂ in THz technology.