Large area CMOS compatible near-IR metamaterials

One of the most important factors that served to facilitate the breakthroughs in the field of optical metamaterials over the last decade has been the development of novel fabrication processes, which enable realization of devices with nanometer scale features. Thus, metamaterials with near-IR and higher operational frequencies have been made possible. These devices can potentially usher in an entirely new generation of optical elements, which can revolutionize technologies in the areas of computing, data storage/processing, and communications.;Despite the exotic properties that optical metamaterials exhibit and the tremendous promise they hold, such materials are still far from widespread implementation. This is due to the fact that the fabrication processes for these structures are not compatible with existing semiconductor processing technologies. Thus, batch fabrication of large area near-IR metamaterial devices has not been possible. The primary goal of this dissertation is to address this fundamental problem with regards to two prominent types of metamaterial structures, namely, (i) "woodpile" photonic crystals for near-IR wavelengths and, (ii) double negative near-IR "fishnet" metamaterials.;The first part of this dissertation presents research conducted with "woodpile" photonic crystal structures for near-IR wavelengths. As such, simulation results, generated using the plane wave expansion method, are presented for a configuration of "woodpile" structure which exhibits "superprism" effect around 1500nm wavelength. Subsequently, the simulated structure is realized using a fabrication process which can produce highly uniform, large area 3D periodic structures with nanometer scale features. This fabrication process utilizes the enhanced absorption properties of the SU-8 photoresist for deep-UV wavelengths to achieve UV exposure confinement to desired resist thicknesses. Additionally, this process makes use of the high resistance of crosslinked SU-8 resist to solvents for layer-upon-layer resist application and processing. There are a number of unique advantages that this fabrication method has to offer. For example, this process is carried out on a layer by layer basis, which allows for the flexibility to incorporate arbitrary design patterns and defect structures for any given layer. Also, depending on the area of the available exposure mask, this process can lead to the development of devices spanning wafers-scale areas. Furthermore, this method of fabrication is compatible with standard semiconductor processing techniques rendering it suitable for mass fabrication.;The second part of this dissertation focuses on double negative near-IR "fishnet" metamaterials. A fabrication method for processing of large area (2mm x 2mm) fishnet metamaterial structures for near-IR wavelengths is presented. This process comprises: (a) defining a sacrificial Si template structure onto a quartz wafer using deep-UV lithography and dry etching, (b) deposition of a stack of Au-SiO2-Au layers followed by, (c) a "lift-off" process which removes the sacrificial template structure to yield the fishnet structure. The fabrication steps in this process are compatible with current semiconductor processing technology, making it suitable for batch fabrication. Furthermore, depending on the area of the exposure mask available for patterning the template structure, this fabrication process can potentially lead to optical metamaterials spanning wafer-size areas.;For characterization of the fabricated "fishnet" metamaterial structures, a Michelson-interferometer based method has been developed, which uses principles of walk-off interferometry. This method allows for simultaneous characterization of the metamaterial structure and an appropriate reference medium during complex transmission and reflection measurements. The complex transmission and reflection data are, thereafter, used to obtain relevant effective optical parameters of the metamaterial structure using well-established formalisms. These characterization results establish that the fabricated structures have a negative refractive index around 1500nm and are double negative. Moreover, the results also compared favorably with simulation results obtained using rigorous FDTD analysis.