We investigate anisotropic two-photon absorption (TPA) effects in a cubic-symmetry crystal excited by scalar and vectorial optical fields. First, we present the anisotropic TPA coefficient, which depends on the anisotropy coefficient, the dichroism coefficient, the crystal orientation angle, and the ellipticity of the polarized ellipse. Second, we develop the elliptically polarized light Z-scan technique for characterizing anisotropic two-photon absorbers, which is demonstrated experimentally. Last, we present the laser beam shaping of vectorial optical fields with Gaussian intensity distribution into a flat-top profile through anisotropic TPA effects. It is shown that the anisotropic TPA offers a new avenue to manipulate the intensity distribution of the polarization-structured light field, which may find interesting applications in beam shaping, optical limiting, and photodetection.

中文翻译：

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Z扫描技术测量各向异性双光子吸收剂及其在激光束整形中的应用

我们研究了由标量和矢量光学场激发的立方对称晶体中的各向异性双光子吸收（TPA）效应。首先，我们提出各向异性TPA系数，该系数取决于各向异性系数，二向色系数，晶体取向角和极化椭圆的椭圆率。其次，我们开发了椭圆偏振Z扫描技术来表征各向异性的双光子吸收体，这在实验中得到了证明。最后，我们通过各向异性TPA效应，将具有高斯强度分布的矢量光场的激光束整形为平顶轮廓。结果表明，各向异性TPA为控制偏振结构光场的强度分布提供了新途径，这可能会在光束整形中找到有趣的应用，