利用半经验色散公式,研究了太赫兹(THz)高频范围的模式色散和LT-GaAs光导开关(PCSS)的辐射衰减特性,并用快速傅里叶变换(FFT)对LT-GaAs衬底共平面微带传输线超短电脉冲的时域传输特性进行了数值计算。结果表明,THz高频范围的模式色散,LT-GaAs衬底的辐射衰减使超短电脉冲波形发生畸变,初始电脉冲越窄,则信号畸变越严重。减小衬底厚度可以降低LT-GaAs衬底共平面微带传输线的模式色散和辐射衰减,从而可以改善LT-GaAs衬底共平面微带传输线超短电脉冲的传输特性。

The semi-empirical dispersion formula was applied to analyze the mode dispersion and Cerenkov radiation attenuation characteristics of coplanar striplines on LT-GaAs substrate in the frequency domain over a terahertz range. Also,FFT was employed to numerically model the time domain propagation characteristics of ultrashort electrical pulse along the coplanar striplines on LT-GaAs substrate. The results reveal that distortion will appear in the waveform of the ultrashort electrical pulse because of the mode dispersion and Cerenkov radiation attenuation mentioned above at frequency range over THz. The shorter the width of the original pulse is,the more serious the distortion becomes. The reduction in the thickness of the LT-GaAs substrate can weaken the mode dispersion and Cerenkov radiative attenuation,and as a result,the propagation characteristics of the ultrashort electrical pulse along the coplanar striplines on LT-GaAs substrate is improved.