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提出了采用双非线性硒化锌(ZnSe)晶体将高斯光束整形成局域空心光束(LHB)的新方案,根据惠更斯-菲涅耳衍射理论计算了不同厚度的ZnSe晶体和不同束腰半径的高斯光束条件下产生的LHB的强度分布和暗斑尺寸。结果表明,该方案产生的LHB强度分布形状为空心椭球体,在传播方向上的二维强度呈中心对称分布。利用数值计算获得了所产生的LHB暗斑的纵横比,发现纵横比随着入射高斯光束束腰半径的增大呈线性增大。该方案产生的LHB的参数可以被灵活调节,因此所产生的LHB可应用于一些较大尺寸的原子分子、生物分子和介质粒子等的光学非接触式囚禁与操控。
A new scheme of shaping the Gaussian beam into a local hollow beam (LHB) using double nonlinear ZnSe crystals was proposed. According to the Huygens-Fresnel diffraction theory, ZnSe crystals with different thicknesses and different beam waist LHB intensity distribution and dark spot size produced under a Gaussian beam of radius. The results show that the shape of LHB intensity produced by this scheme is a hollow ellipsoid, and the two-dimensional intensity in the direction of propagation shows a centrosymmetric distribution. The aspect ratio of the generated LHB dark spots was obtained numerically. It was found that the aspect ratio increased linearly with the increase of the waist radius of the incident Gaussian beam. The parameters of the LHB produced by this solution can be flexibly adjusted. Therefore, the generated LHB can be applied to the optical non-contact captivity and manipulation of some larger-sized atomic molecules, biological molecules and medium particles.