论文部分内容阅读
利用二维ensemble-MonteCarlo方法模拟了直流偏置的半绝缘GaAs(SI-GaAs)光电导开关在飞秒激光脉冲触发下的两种工作模式.结果表明:当偏置电场低于耿氏电场(GaAs为4.2kV/cm)时,开关输出电脉冲呈线性模式;偏置电场超过耿氏电场但触发光脉冲能量低于光能阈值,光电导开关仍然表现出线性工作模式;当偏置电场和触发光脉冲能量都超过非线性模式(“lock-on”模式)所需阈值,开关呈现非线性模式;在光子能量较高的激光脉冲触发下,开关非线性模式所需光能阈值降低.非线性工作模式源于光生载流子发生谷间散射,并在开关体内局部区域形成高场区,电场变化大,弛豫时间长,电脉冲呈现非线性.
Two kinds of operating modes of DC bias semi-insulating GaAs (SI-GaAs) photoconductive switches triggered by femtosecond laser pulses are simulated by two-dimensional ensemble-Monte Carlo method. The results show that when the bias electric field is lower than Gunn’s electric field GaAs 4.2kV / cm), the output pulse of the switch is in a linear mode. When the bias electric field exceeds the Gunn’s electric field but the energy of the triggered pulse is lower than the light threshold, the photoconductive switch still exhibits a linear operating mode. When the bias electric field and The switch triggers a non-linear mode with the energy of the triggering optical pulse that exceeds the threshold required for the non-linear mode (“lock-on” mode). The threshold of light energy required to switch the non-linear mode is reduced by the laser pulse with higher photon energy The non - linear operating mode originates from the scattering of photogenerated carriers between the troughs and forms the high field region in the local area of the switch body, the electric field changes greatly, the relaxation time is long, and the electrical pulse is nonlinear.