量子尺寸相关的金纳米环三阶非线性光学极化增强

基于金属颗粒与电磁场相互作用的Mie理论和非线性光学的基本原理，利用束缚元法等方法计算得到了不同环壁厚度下金纳米环的三阶极化率增强因子．当金纳米环壁厚度d逐渐减小时（d／a由1→0，其中a为环半径），其表面等离子共振吸收频率由684nm逐渐红移，且速率逐渐增大，而且其等离子共振频率处三阶极化率增强因子F^（3）（ωR）随着环壁厚度的减小先增大，而后逐渐减小（d／a≈0．2时，F^（3）（ωR）达到最大）．金纳米环的这种性质，为制备非线性光学器件提供了理论基础．

Quantum Size Dependent Third-Order Nonlinear Optical Polarization Enhancement of Gold Nano-Rings

The optical third-order nonlinear enhancement factors of gold nano-rings with different thickness of ring walls have been calculated by using the boundary elements method,based on the principle of nonlinear optics and the theory of interaction between metal particles and electromagnetic field.It is shown from the calculation results that with the decreasing of the thickness of the ring walls(d/a from 1 to 0),the wavelength of gold nano-ring's surface plasma resonance gets red shift from about 684 nm gradually.However,the third-order optical nonlinear enhancement factor increases to the maximum when d/a at about 0.2 and then decreases during the decreasing of the ring walls' thicknesses.Devices with relatively strong nonlinear optical effect can be made basing on such property of gold nanorings.