The photoconductive antenna (PCA) is one of the most common devices to generate terahertz (THz) wave, whose radiation efficiency is largely determined by the working conditions. In order to improve the power of THz wave, the influence of pump laser and bias voltage on the intensity of the THz wave radiated by PCA was studied through experiment and the optimum working conditions of PCA was obtained through the theoretical analysis, these are the maximum safe voltage and saturated laser energy. Only under the optimum conditions can the signal-to-noise ratio(SNR)of THz wave radiated by PCA be the highest and the PCA would not breakdown.
By adding different inductance to the bias voltage circuit of the photoconductive antenna, the changes of the time-domain waveform peak value and spectral bandwidth of THz radiation from the photoconductive antenna were observed, and further studied the influence on the characteristics of THz radiation from the inductance of photoconductive antenna circuit when designing the photoconductive antenna. According to the experiments, it is found that different inductance values have no prominent effect on the peak value of time-domain waveform and spectrum bandwidth of THz radiation from the photoconductive antenna.
To analyze the carrier lifetime of Si, a 0.4 mm thickness high-resistivity silicon had been investigated by the optical-pump-terahertz-probe (OPTP) system. The terahertz time domain curve and frequency spectrum (bandwidth of > 6THz) of Si are achieved by the time domain spectroscopy mode, and its characteristic parameters, including refractive index and absorption coefficient, were obtained. And the carrier lifetime of Si was measured by the OPTP mode, the result is about 905 ps.
In this paper, cross-linked polyethylene (XLPE) was analyzed by THz time domain spectroscopy (TDS) system at room temperature. By recording time domain signal of terahertz radiation field, frequency spectrum can be obtained by Fourier transform. Then the refractive index and dielectric constant in THz band are calculated. This proves that the THz-TDS system has a potential application for detecting the aging characteristic of XLPE.