The Study Of Photoconductive Antenna Generated THz Wave

Based on the special position in electromagnetic spectrum, THz is widely used in many fields, such as imaging, environment supervising, medical diagnosis, radio astronomy, satellite communications and military radar and so on. But lacking in high-power THz source has seriously blocked the technology progress of THz.Based on THz wave characteristics, the methods of generation and detection of THz wave, the technology of electro-optic sampling and improving the power of THz radiation have been investigated.The semi-conductive GaAs dipole antennas are passivated by Si₃N₄ and the bare antennas experiments are contrasted. The carriage principle of carriers biased by DC field in GaAs photoconductive has been simulated by Monte Carlo. The out-coming THz power can be improved in condition of photoconductive antennas biased by higher DC electric field with the same laser energy. The reason is that the carriers inside antennas are affected by stranger electric force. The power of THz wave will increase with the more laser energy in the same bias electric field. Because of the shielding affection of space charge, the increasing of the THz power is not according to the square of the number of photoconductive on carriers. The large aperture can bear more carriers, so that the THz power of large aperture antennas is higher than that of small-bore antennas. In condition of neglecting the shielding affection, the life of the carriers and the laser play important role in radiation of THz wave. The longer the trapping time of carriers, the higher the power of THz radiation. Meanwhile, the shorter the wavelength of incident laser pulse, the higher the power of THz radiation.During the process of building the model, because the life of carriers and the pulse width of laser are taken into account in the model, these factors on the impact of THz radiation have been summarized by changing the parameters. It is important to design the new experiments to generate high-power THz radiation by using of photoconductive dipole antenna.