外加交变电场对光折变基频空间电荷场瞬态特性的影响

利用“跳跃模型”讨论外加交变电场（包括正弦和方波电场）对光折变基频空间电荷建立的影响，给出了空间电荷场基频分量随时间、外加交流电场振幅频率等变化的通解表达式。发现基频空间电荷场虎部和实部的振荡频率分别是外加交流电场振荡频率的两倍和一倍。当外加交变电场频率较大时光折变光栅是相移型的。这和基于“带导模型”给出的数值结果相符。

Effect of External Applied Alternating Field on the Transient Behaviour of Fundamental Harmonic of Photorefractive Space-Charge Field

The “hopping” model is used to analyze the transient behaviours of fundamental harmonic of the space-charge field with external AC field. Exact and approximate dynamic analytical solutions are presented in the presence of sinusoidal AC field and square-wave field. For the applied AC field, it is found that the real part of the fundamental space-charge field varies at the same frequency as that the applied field does, the imaginary part oscillates at twice the frequency. The photorefractive grating is phase-shift for high frequency of external applied alternating field. These results are in agreement with those derived from the band -transport model.