Figure 5

The time-domain amplitude dependences on the pump power, the azimuthal angle of the crystal and the excitation power on the PC antenna.

(a) The THz amplitude increases linearly as the pump power rises. A linear fitting based on is shown in solid line, where α is a coefficient to simply contain all other factors that have no relation with the pump power. (b) The amplitude modulation when the crystal was rotated along its surface normal. Two maximum amplitudes are obtained at θ = −90°, 90°, where θ is the angle between b-axis and the polarization of the pump beam. (c) The THz time-domain amplitude increases linearly as probe power rises from 5 mW to 20 mW and turns to saturation when the probe power goes higher.