以InGaAs pin管为例，研究了光电二极管在激光脉冲作用下非线性响应的内部机理特征，计算分析了二极管在强光辐照下内部空间电荷屏蔽效应对器件光电响应特性产生的影响.通过计算耗尽区的电场强度、载流子分布和电子空穴的漂移速度，发现低偏置电压或强光辐照都会使耗尽区的电场强度下降，载流子的漂移和扩散速度降低到非饱和状态，使光生载流子的复合率下降，大量载流子聚集在耗尽区内，形成了空间电荷屏蔽效应，导致二极管呈非线性响应状态.在5 V偏置电压条件下，增加皮秒激光的脉冲能量，光电二极管的光伏电压响应脉宽逐渐展宽，峰值电压呈非线性变化.

To study the internal mechanism of the photodiode nonlinear response to the high energy laser pulse, the influence of the space charge screening on the photoelectric response characteristic of the InGaAs pin photodiode was calculated under the high optical injection. The electrical field, distribution of carriers and electronhole mobility in the depletion region were calculated respectively. The simulated results indicate that when the applied bias field is low or the laser pulse energy is high, the electrical field in the depletion region is suppressed and the driftdiffusion velocity is reduced to the unsaturated state. Therefore, the separation and recombination of the holeelectron is slowed down, lots of the photocarriers is in the depletion region, which leads to the nonlinear response due to the space charge screening. In the experiment, the InGaAs pin photodiode′s response voltage pulse width is widening and the peak voltage is increasing nonlinearly with the increasing 20 ps laser pulse energy in the 5 V applied bias. The calculation of the photodiode internal mechanism is proved to be valid by the experimental phenomena.