Photonic crystal (PhC) structures with appropriate characteristics are necessary to control spontaneous emission from fluorophores while designing miniaturized lasers. We report the fabrication and detailed studies on the emission features of two different spectrally engineered PhC heterostructures made from dye-doped opal and one-dimensional (1-D) multilayer stack. Our results demonstrate notable enhancements of emission from PhC heterostructure enabled by the stopband overlap of three-dimensional (3-D) opals and 1-D multilayers. In the presence of the 1-D multilayer, the distributed feedback from opals further enhances the emission from the dye. We emphasize the role of the interplay of the spectral overlap of stopbands and the band edges in the dye-doped PhC heterostructures to control their emission features. The emission results obtained from our heterostructures are very much dependent on the relative spectral position of the stopbands of the constituent 1-D and 3-D photonic crystals. Input pump energy-dependent emission results indicate that such heterostructures are potential candidates for designing colloidal PhC-based lasers.
Due to its high sensitivity and selectivity, UV resonance Raman (UVRR) spectroscopy has a number of scientific and industrial applications. Deep UVRR excited within explosive absorption bands (200 – 230 nm) enables trace explosive detection at a distance due to the resonance enhancement of Raman band intensities, stronger light scattering at short wavelengths, as well as negligible florescence interference.
We are developing deep UVRR detection methodologies by investigating resonance enhancement of explosives excited in the deep UV, determining the optimal excitation wavelengths, investigating explosive UV-photochemistry, characterizing explosive UV photoproducts, and measuring UVRR spectral evolution during explosive photolysis.
We are also developing state-of-the-art UVRR instrumentation by designing and manufacturing high efficiency, high throughput standoff UVRR spectrometers, co-developing new compact solid state deep UV lasers, and designing novel deep UV optical diffracting devices.