Comparative study on THz time-domain spectroscopy using 780-nm 1.3-ps laser pulses with different detections of LT-GaAs photoconductive antenna and ZnTe electro-optic sampling

Abstract

We have demonstrated the comparison of terahertz (THz) time-domain spectroscopy (THz-TDS): a low-temperature grown GaAs photoconductive antenna (PCA) and ZnTe electro-optic (EO) sampling with 780-nm 1.3-ps laser pulses. As a result, the different detection limits up to approximately 0.8, 1.0, and 1.3 THz are obtained with a bow-tie, dipole antenna, and ZnTe crystal, respectively. In the PCA sampling, the frequency at main peak of the spectrum measured with the dipole antenna is higher than the one with the bow-tie antenna. The dynamic range of the power spectrum measured with the bow-tie antenna is higher than any other detection methods. In addition, we compare the PCA sampling with femtosecond laser pulses to the one with picosecond laser pulses in terms of the response of the PCAs.