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Abstract:
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The control and manipulation of infrared (IR ) radiation beyond the capabilities of natural materials using silicon carbide (SiC ) , metamaterials , or a combination thereof , is presented . Control is first demonstrated using SiC , a polar crystal that exhibits a dielectric permittivity less than zero in the mid -IR range , through the excitation of tightly confined surface phonon -polaritons (SPPs ) , thus enabling a multitude of applications not possible with conventional dielectrics . Optimal , or critical coupling to SPPs is explored in SiC films through Otto -configuration attenuated total reflection . One practical application based on Otto -coupled SPPs is presented : IR refractive index sensing is shown for three pL -scale fluid analytes . It is then demonstrated that when two SiC films are brought to a few -micron separation , IR radiation can excite surface modes that possess phase velocities near the speed of light , a property required for efficient table -top particle accelerators . Metamaterials are engineered with subwavelength structure and possess optical properties not found in nature . Two such metamaterials will be introduced : metal films perforated with arrays of rectangular holes display the ability to control IR light polarization through spoof surface plasmon excitation , and metal /dielectric multilayers
patterned with subwavelength -pitch corrugations display frequency -tunable , wide -angle , perfect IR
absorption . Two experiments , which have implications in polarization control and thermal emission , combine the benefits of SiC with those of metamaterials : extraordinary optical transmission and absorption are observed in SiC hole arrays , and the design of individual SiC antennas permits the
control of the bulk metamaterial responses of impedance and absorption /emission . Finally , a new
optical beamline based on Fourier transform IR spectroscopy was designed , built , characterized , and
implemented , serving as the major experimental objective of this dissertation . The novel beamline ,
which confines radiation to a 200 -micron diameter and enables angle -dependent IR spectroscopy , was verified using multiple metamaterial structures . |