| This thesis describes a study on tapered air-core Bragg waveguides for use as integrated micro-spectrometers in lab-on-a-chip systems. Position-dependent cutoff of the leaky waveguide modes results in spatial dispersion of polychromatic input light. These devices may be viewed as side-coupled Fabry-Perot cavities of varying core thickness. Chip-scale spectrometers have a number of applications, including point-of-care diagnostics, biochemistry, and field-deployable threat detectors.;Bragg cladding mirrors with an omnidirectional band (for TE-polarized light) between ~490 nm and ~570 nm were deposited using both e-beam evaporation and reactive sputtering. Using these claddings, tapered hollow Bragg waveguides were assembled using two different methods: buckling self-assembly and a wafer-bonding process. The tapers exhibited resolutions ranging from ~2.2 nm to ~0.8 nm, for mode orders m = 1 to m = 8. Implementing the tapers in a prototype sensing system, the fluorescence spectra of individual fluorescent beads were successfully measured over the ~70 nm wide operating range of the device. |
