Study on Closed-aperture Z-scan Diffraction Theory for Large Optical Nonlinear Absorption Phase Shift
基于衍射理论的大非线性相移Z扫描研究

Based on Fresnel-Kirchhoff diffraction theory,a diffraction model of nonlinear optical media to gaussian beam was built for larger optical nonlinear absorption phase shift.Numerical results show that the peak of the transmittance is greatly enhanced and the valley is suppressed with larger refraction phase shift.While the large absorption phase shift makes the peak of transmittance severely suppressed and the valley greatly enhanced.The ratio of these two phase shifts decide whether the valley-peak structure is existed.The far-field output power is not completely increased with the increasing nonlinear absorption coefficient.This theory is more accurately than the conventional Z-scan theroy because the applicable condition is only thin sample.