四光束干涉单次曝光构造含平面缺陷三维周期性微纳结构

本文使用多光束干涉方法构造三维周期性微纳结构.通过多次匀胶与单次曝光结合, 在负光刻胶SU8上刻蚀出含平面缺陷的类金刚石结构(fcc-like)光子晶体.扫描电子显微镜(SEM)观测显示, 相比无缺陷光子晶体结构,该结构在(111)晶面上存在清晰可见的平面缺陷.通过控制匀胶时的转速, 可以精确控制平面缺陷厚度在适合的范围.傅里叶红外反射光谱测试显示完整周期微纳结构在(111)方向上 有明显的特征峰,两个特征反射峰中心波长接近1.2 μm和2.4 μm. 含缺陷的结构则在反射光谱特征峰中掺入了明显的凹陷,并且随着平面缺陷的厚度增大, 缺陷模从处于2.4 μm禁带移至1.2 μm禁带处.提取SEM图中的结构参数, 用FDTD方法模拟分析,发现模拟结果与实验值基本一致,证明了平面缺陷不但存在,而且面积较大.

Fabricating three-dimensional periodic micro-structure with planar defects via a single exposure

In this paper, we introduce a method to incorporate a planar defect into the fcc-like photonic crystal structure by utilizing a negative photoresistor SU8. This method in which multi-coating and a single exposure are used simplifies the experiment much more than other methods. In the paper, we exhibit the SEM images for the intact and defective structures. Corresponding to each structure, the reflection spectrum in (1 1 1) direction fabricated shows obviously characteristic peaks and pits. For the intact structure, the spectrum contains two peaks whose wavelengths approach to 1.2 μm and 2.2 μm. These two peaks corresponds to two optical forbidden gaps. For the structure with planar defect, a pit which splits the optical forbidden gap is considered to be a defect mode exhibited on spectral curve. The structure parameters are extracted from the SEM image and used to simulate the reflectance spectra via FDTD program. The simulation results almost match the experiment data accurately.