Manipulation of terahertz pulse generation in ZnTe crystal by shaping femtosecond laser pulses with a square phase modulation

We theoretically demonstrate that the terahertz pulse generation via optical rectification in ZnTe crystal can be effectively controlled by making use of the shaped femtosecond laser pulses with a square phase modulation. We show that, by precisely controlling these parameters characterizing the square phase modulation, the terahertz spectrum is periodically modulated and the terahertz pulses are split into multiple subpulses, and the modulation period of the terahertz spectrum and the relative intensity and time interval of these terahertz subpulses can be continuously tuned. Furthermore, we utilize the power spectrum of the shaped femtosecond laser pulses to explain the physical control mechanism of the shaped and tunable terahertz pulse generation.