Artificial Dielectrics: Hybrid Structures for MID-IR Applications

无源薄膜的介电特性可以通过在薄膜中加入微小的散射特性来调整。人工介电体是通过将导体作为精细结构嵌入到介电材料中来实现的。同样的概念也适用于互补模式，即在薄金属薄膜内放置一组非常小的孔。这个概念是特别感兴趣的中红外波长区域，各种透明的介电材料是相当有限的。此外，为诸如带通滤波器或谐振器之类的系统量身定制色散特性对于化学和生物表征非常重要。在这个光谱区域只有很少的结构被发现，我们打算以系统的方式探索它。尽管在理解微波和远红外区域的波传播方面已经投入了大量的理论努力，但直到最近P. Lalanne才在2-5微米区域建立了一个适当的模型。高纵横比光刻胶的最新发展使得利用光刻技术制造复杂结构变得非常有吸引力。此外，由于可以使薄膜的厚度大于传播波长，因此可以实现近场和远场元件。因此，我们建议在中红外波长区域分析和制造由介电或金属薄膜（人工介电）内的小散射特征堆叠而成的色散元件。这些特征将被构建为混合结构（金属/介电组合）的周期性阵列，散射元素远小于传播波长。我们特别建议对混合结构的特性进行分析和实验研究，例如波前分束分束器。研究了带通滤波器的谐振特性，两种杂化结构在Fabry-Perot构型下的谐振结构，以及杂化结构叠层作为三维人工电介质的色散特性。样品将在NJIT的10级洁净室中使用特殊的Si键合和深度反应离子蚀刻设备进行生产。近场和远场测量将在NJIT的电子成像中心进行，使用IR-CCD相机（Samoff， 3-5微米）与SUN工作站接口，以获取和处理不同集成时间的图像

9820200GrebelThe dielectric properties of passive thin films can be tailored by incorporating small scattering features within them. Artificial Dielectrics (ADs) are achieved upon the embedment of conductors as fine structures within dielectric materials. The same concept works in the complementary mode where an array of very small holes are placed within a thin metal film. This concept is of particular interest in the mid-IR wavelength region where the variety of transparent dielectric materials is quite limited. Moreover, tailoring the dispersion properties for systems such as band-pass filters or resonators is extremely important for chemical and biological characterizations. Only a very few structures have been realized in that spectral region and we intend to explore it in a systematic manner. Although much theoretical effort has been invested in understanding the wave propagation in the microwave and far infrared region, only recently an adequate model was constructed in the 2-5 microns region by P. Lalanne. Recent developments in high aspect ratio photoresists make it very appealing to fabricate complex structures using photo lithography. Moreover, since the thickness of the film may be made larger than the propagating wavelength, near-field and far-field elements may be realized. We, therefore, propose to analyze and fabricate dispersion elements made of stacks of small scattering features within dielectric or metal films (Artificial Dielectrics) for mid-IR wavelength region. These features will be constructed as periodic arrays of hybrid structures (metal/dielectric combination) with scattering elements much smaller than the propagating wavelength. In particular we propose to study analytically and experimentally the properties of hybrid structures, such as wavefront dividing beamsplitters. The resonance's of band pass filters, the resonance structure of two of these hybrid structures in a Fabry-Perot configuration, and the dispersion properties of stacks of hybrid structures as 3-D artificial dielectrics. The samples will be produced in the class 10 clean room at NJIT using special facilities for Si bonding and deep reactive ion etching. Near and far-field measurements will be performed at the Electronic Imaging Center at NJIT, making use of an IR-CCD camera (Samoff, 3-5 microns) interfaced with a SUN workstation to acquire and process images with various integration times.***