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实验证实飞秒激光在透明材料内部诱导的周期性纳米条纹具有特殊的光学特性。采用时域有限差分方法(FDTD)分别对单元纳米光栅和纳米光栅阵列的散射特性进行研究,分析结果显示纳米光栅的散射对入射激光的偏振方向敏感;散射强度与入射激光波长相关,波长越长、散射越弱。对于纳米光栅阵列,平行于纳米光栅的散射强度比垂直于纳米光栅的散射强度小两万倍。最后从理论上验证了Ⅱ类波导和纳米光栅偏振导光是由纳米光栅的散射引起的而不是双折射效应。
Experiments confirmed that the periodic nano-stripes induced by the femtosecond laser in the transparent material have special optical properties. The scattering characteristics of nanoscaled gratings and nanowire arrays were investigated by FDTD method. The results show that the scattering of nanorods is sensitive to the polarization direction of incident laser light. The scattering intensity is related to the incident laser wavelength, and the longer the wavelength , The weaker the scattering. For nanowire arrays, the scattering intensity parallel to the nanowires is 20,000 times smaller than the scattering intensity perpendicular to the nanowires. Finally, it is theoretically verified that the guided waveguides of the type II waveguide and the nanorod polarization are caused by the scattering of the nanorod rather than the birefringence effect.