Artificial Dielectrics: Hybrid Structures for MID-IR Applications

9820200Grebel无源薄膜的介电性能可以通过在其中加入微小的散射特性来定制。人工介质(ADS)是通过将导体作为精细结构嵌入到介质材料中而实现的。同样的概念也适用于互补模式，即在一层薄的金属薄膜中放置一组非常小的孔。这一概念在中红外波段特别有意义，在那里透明介质材料的种类非常有限。此外，为带通滤光器或谐振器等系统量身定做色散特性对于化学和生物表征是极其重要的。在该光谱区域只实现了极少数结构，我们打算以系统的方式对其进行探索。虽然在微波和远红外区的波传播已经投入了大量的理论工作，但直到最近P.Lalanne才在2-5微米范围内建立了一个合适的模型。高深宽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，我们建议分析和制作由介质或金属薄膜(人工介质)内的微小散射特征堆叠而成的中红外波段的色散元件。这些特征将被构建为具有比传播波长小得多的散射元素的混合结构(金属/介质组合)的周期性阵列。特别是，我们建议对混合结构的特性进行解析和实验研究，例如波前分割分束器。研究了带通滤光片的谐振特性，其中两种混合结构的谐振结构，以及作为三维人工介质的混合结构堆叠的色散特性。样品将在NJIT的10级洁净室中生产，使用特殊的硅键合和深度反应离子刻蚀设备。近场和远场测量将在NJIT的电子成像中心进行，利用与SUN工作站连接的IR-CCD相机(Samoff，3-5微米)获取和处理不同积分时间的图像。*

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.***