Terahertz pulse shaping via birefringence in lithium niobate crystal

Terahertz time-domain spectroscopy (THz-TDS) is employed to study the spectral response of lithium niobate crystal. A giant birefringence occurs in lithium niobate crystal in the THz frequency region. We demonstrate that the waveform of the THz wave is controllable by use of the birefringence property of the crystal. We also show experimentally that one THz pulse can be separated into two coherent sub-pulses; the separation as well as the relative intensity of the two sub-pulses are adjustable by changing the crystal orientation with respect to the polarization of the THz beam.