基于光子晶体的Kretschmann结构中自准直光束的Goos-Hänchen位移研究

利用平面波展开法和时域有限差分法, 模拟研究了基于自准直条件下的高斯光束入射光子晶体Kretschmann结构时发生的同时具有正向和负向Goos-Hänchen位移的双束反射现象. 研究表明, 反射光束中具有一束较小的正向位移, 而另一束具有较大的负向位移, 发现当Kretschmann结构支持的泄漏的表面模式被激发时才出现这一特殊现象; 表面模式的场分布说明介质波导中存在着强局域稳态场, 大的位移来自于表面模式与自准直体模式间的强耦合, 同时探讨了表面模式与光子晶体自准直体模式之间发生耦合的条件和影响参数. 本文负向位移最大达到-23.23a(a为晶格常数), 对应入射光波长的4.99倍, 是束腰半径的1.1615倍. 关键词： 光子晶体 自准直 Kretschmann结构 Goos-Hä nchen位移

Goos-Hänchen shift of self-collimated beam in Kretschmann configuration based on photonic crystal

We perform the finite-difference time-domain (FDTD) simulations and analyze a dual-beam-reflection phenomenon for a Gaussian beam illuminating a Kretschmann configuration composed of a lossless dielectric waveguide between a photonic-crystal-made prism and air. One reflection beam has a small positive shift and the other has a large negative shift in the dual-beam-reflection phenomenon. The FDTD shows that the specific phenomenon takes place just when the corresponding leaky surface mode supported in the Kretschmann configuration is excited. Field profile of the surface mode demonstrates a strong localized stationary field in the dielectric waveguide. We find that the maximum negative lateral shift is -23.23a, corresponding to 4.99 times of the incident wavelength, which is 1.1615 times of the beam waist.