Acta Photonica Sinica, Volume. 34, Issue 7, 1010(2005)
A Z-Scan Theory Based on Diffraction Theory with Consideration of Two-photon Absorption
Based on Fresnel-Kirchhoff diffraction theory, a diffraction model of a nonlinear optical medium to a Gaussian beam is built. The propagation behavior of the Gaussian beam passing through the nonlinear optical medium is theoretically deduced and numerically simulated, which can explain the Z-scan phenomenon from a new approach. From this theory, a unified equation is derived, which can describe both the closed-aperture Z-scan curve and the open-aperture Z-scan curve with consideration of the two-photon absorption. It provides a new way to calculate the nonlinear refraction index and the two-photon absorption coefficients. Numeric simulation shows that for the closed-aperture Z-scan considering the two-photon absorption, the simulation results are well consistent with the conventional theory. For a given open-aperture Z-scan curve, the two-photon absorption coefficient computed by the new Z-scan theory is 1/3 of the value fitted by the conventional Z-scan theory, whereas other conclusions are identical to the......
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[in Chinese], [in Chinese], [in Chinese]. A Z-Scan Theory Based on Diffraction Theory with Consideration of Two-photon Absorption[J]. Acta Photonica Sinica, 2005, 34(7): 1010