周期结构金属薄膜的奇异光学性质

Extraordinary Optical Properties of Periodically Perforated Metal Films

二维亚波长周期结构金属薄膜具有光透过率异常增强的现象,某些情况下,这种薄膜的峰值透过率比根据传统小孔理论计算的预测值高3个量级.这种结构的金属薄膜在光印刷、近场显微镜和光子器件等方面有着广泛的应用前景,近年来引起了人们的重视.根据目前的实验研究报道,这种周期结构金属薄膜通常利用聚焦离子束刻蚀工艺来获得,器件的光学响应在可见光波段和近红外波段.利用镂空模板法制备了周期结构金属薄膜.实验表明,制得的器件在红外波段也具有透过率异常增强的现象,且利用这种方法易于获得大面积对称结构和串联结构的器件.

Metal films with two-dimensional periodic arrays of sub-wavelength apertures can exhibit extraordinary optical transmission. In some cases, the transmission enhancement can be three orders of magnitude greater than what is predicted by the standard aperture theory. There has been a great interest in such structured films due to its potential applications in photolithography, near field microscopy and photonic devices. In most of the experiments reported to date, the perforated metal films were fabricated by the focused-ion-beam method, and their transmission enhancement was in the visible and near-infrared regions. According to our research, a stencil mask method can be used to fabricate such perforated metal films. Our experiments demonstrated that the devices made with this method can also induce transmission enhancement in the middle-infrared region. Moreover, large-scale and the cascaded structures can be easily obtained by our method.