The 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.
|Effective start/end date||6/1/99 → 5/31/03|
- National Science Foundation: $240,000.00