Agrawal A, Matsui T, Zhu W, Nahata A, Vardeny Z V
Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah 84112, USA.
Phys Rev Lett. 2009 Mar 20;102(11):113901. doi: 10.1103/PhysRevLett.102.113901. Epub 2009 Mar 18.
We use terahertz time-domain spectroscopy to study the transmission properties of metallic films perforated with aperture arrays having deterministic or stochastic fractal morphologies ("plasmonic fractals"), and compare them with random aperture arrays. All of the measured plasmonic fractals show transmission resonances and antiresonances at frequencies that correspond to prominent features in their structure factors in k space. However, in sharp contrast to periodic aperture arrays, the resonant transmission enhancement decreases with increasing array size. This property is explained using a density-density correlation function, and is utilized for determining the underlying fractal dimensionality, D(<2). Furthermore, a sum rule for the transmission resonances and antiresonances in plasmonic fractals relative to the transmission of the corresponding random aperture arrays is obtained, and is shown to be universal.
我们使用太赫兹时域光谱技术来研究具有确定性或随机分形形态（“等离子体分形”）的孔径阵列穿孔的金属薄膜的传输特性，并将其与随机孔径阵列进行比较。所有测量的等离子体分形在与它们在k空间中的结构因子的显著特征相对应的频率处都显示出传输共振和反共振。然而，与周期性孔径阵列形成鲜明对比的是，共振传输增强随着阵列尺寸的增加而减小。使用密度-密度相关函数解释了这一特性，并将其用于确定潜在的分形维数D(<2)。此外，还获得了等离子体分形中的传输共振和反共振相对于相应随机孔径阵列传输的求和规则，并证明其具有普遍性。
