Study on Terahertz Emission Properties of Bow-Tie Photoconductive Antenna

The terahertz (THz) emission properties of four kinds of bow-tie photoconductive antennas are studied. The characteristic of THz radiation generated by them is compared. The emission spectra of the photoconductive antennas are obtained by THz time domain spectroscopy (TDS) technology. The corresponding frequency domain spectra are obtained by Fast Fourier Transformation (FFT). The results show that when we increase the bias voltage, the peak value of THz radiation is increased and tends to saturation when the pump power is strong enough. Under the same bias voltage and the pump power, the properties of THz radiation generated by four bow-tie photoconductor antennas are compared. It shows that under low bias voltage, the full width of half maximum (FWHM) of frequency a domain spectrum which is generated by small-aperture bow-tie photoconductor antenna is broader than that of the large aperture one. The gap size of small-aperture photoconductive antenna is smaller, the FWHW is broader. On the other hand, under the high bias voltage, the intensity of THz radiation of the large aperture photoconductor antenna is much larger than the small aperture one. Our results provide a reference to investigate and fabricate the high efficient of THz emission source.