| Several mid-infrared plasmonic devices were developed in this work. The first, and perhaps foremost of these devices is the beaming device; a metal grating with a subwavelength aperture through which light of a specific wavelength transmits with a greatly reduced beam divergence, via interaction with surface plasmon polaritons coupled to on the grating's surface. This device is explored in detail, including both its far- and mid-field behavior, its capacity for being tuned, and modifications to the device design which permit unique beam shaping and focusing. Supplementing this device is an epsilon near zero structure, with the epsilon near zero condition obtained using highly doped semiconductor material. Epsilon near zero material can be used to enhance light coupling into subwavelength apertures, with potential applications in devices such as the aforementioned beaming device. This epsilon near zero structure will be shown to indeed allow for transmission above that of an appropriately chosen reference structure. The final structure which will be presented also utilizes highly doped semiconductor material with a plasma wavelength in the mid-infrared, patterned into micro-structures, in order to sustain localized surface plasmons on the structures. The significance of this effort lies in the fact that localized surface plasmons are not sustainable with mid-infrared light using standard plasmonic materials (noble metals). |
