| In this paper, the characters of THz wave, the progress of THz time domain spectrum detection, THz imaging and the applications, and the methods of generation and detection were introduced in detail.Then the high power of the photoconductor antennas and the design to improve the maximal applied voltage was introduced. By contrasting the designed antennas and the bare antennas by experiments, we found the maximal biased voltage and the radiated THz's intensity of the designed antenna can be greatly improved when triggered by the same energy light pulse.Our studied based on the current surge model of terahertz radiation the influence of screening of the bias field, the exciting optical pulse, time-dependent surface conductivity and time-dependent mobility are also taken into account in the model to describe the terahertz radiation from photoconductor antennas, and then improved the current surge model. Then the screening effect of the terahertz radiated from photoconductor antennas was simulated by the methods of Monte Carlo, and the incident light energy and electrodes gap were analyzed.When the environmental conditions were fixed on and invariable, the terahertz radiation was directly proportional to the bias field. When the shape and the offset of the electrodes of photoconductor antennas changed, the terahertz altered evidently. In this paper, a method to calculate electric field of the difference shape of the electrodes was introduced and the shape of electrodes were improved. The results show that the electric field of the electrodes was affected by the width, the gap distance, and the offset angle of the electrodes. Electric potential was proportional to the width of the electrode, and the different of the offset angle correspond with the different electric field distributing, the offset of the electrodes was important factor. As the antennas was not breakdown by electric field, the intensity of terahertz radiation from the antenna with offset was better than not. |
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