同轴双光束Z扫描的衍射理论

Diffraction theory for collinear dual beam Z-scan

利用菲涅耳衍射原理研究了同轴双光束Z扫描现象,建立了同轴双光束Z扫描的衍射理论模型,并且对大、小非线性相移两种情况进行了数值模拟.研究结果发现,当非线性相移较大时,传统Z扫描理论的计算易出现振荡,而菲涅尔衍射模型则无此缺陷,可用于不同相移情况下的Z扫描实验.

Based on Fresnel diffraction theory, Z-scan phenomena were studied. A diffraction theoretical model was presented for the collinear dual beam Z-scan technique. The Z-scan signal for the large and/or small nonlinear phase shifts resulted from the Kerr effect was numerically simulated by the diffraction model and the conventional Z-scan theory respectively. It was showed that, when the phase shift was large, the irregular oscillation easily appeared in the Z-scan signal simulated by the conventional theory. However, the diffraction model could be applied to the analysis of Z-scan experiments for different nonlinear phase shifts.