Metallic photonic crystals : transmission resonances and second harmonic generation

A metal film with a thickness that reflects essentially all incident light, can be made highly transmissive by perforating the metal film with an array of subwavelength holes. In this dissertation, plasmonic nanostructures are fabricated by interferometric lithography combined with self-aligned processing techniques on several-cm2 area substrates. Experimental investigations include detailed studies of the extraordinary optical transmission, nonlinear second harmonic generation (SHG) and biosensors. We report the first experimental demonstration of > 70% enhanced transmission of a double-layered (metal-dielectric-metal) grating with a complementary capacitive (isolated discs) / inductive (connected film with apertures) structure, even at normal incidence where there is no line-of-sight path through the structure. The interactions of surface plasmon (SP) waves on multi-metal-dielectric thin films are analyzed in detail. The coupling of localized modes and distributed SP modes modulates the local mode positions, amplitudes and phases. Nonlinear SHG based on the enhancement of localized fields confined in nanoscale periodic, GaAs-filled plasmonic structure is presented. The SHG is enhanced by ~ 100x compared to that of GaAs bulk at normal incidence without phase matching. The SHG saturates at 10GW/cm2, due to multi-photon absorption and the resultant free-carrier absorption. Free carriers are monitored by photoluminescence. An extraordinary five photon absorption is observed with a fundamental frequency close to 1/3 of bandgap frequency, which may result from Van Hove singularities of GaAs bandgap structure. We also develop an all-dielectric, two dimensional photonic crystal slab-based sensor to detect refractive index changes in an aqueous solution with high sensitivity (Dlamda = 0.2 nm/Dn = 1.5×10-3), which enables high throughput analysis for medical diagnostics.Electrical EngineeringDoctoralUniversity of New Mexico. Dept. of Electrical and Computer EngineeringBrueck, Steven R. J.Sheik_Bahae, MansoorMalloy, KevinGilmore, Mar