Glancing angle deposition (GLAD) technique was used to make SiO₂ nano-wire layers of refractive index < 1.33 using an e-beam evaporator. Brag reflectors were made using bulk SiO₂ and nano-wire SiO₂ to characterize angle dependence of the refractive index using transmission measurements and confirmed using an ellipsometer (Film Tek 4000SE). Simulations to fit the transmission measurements are done using matrix analysis of planar dielectric layers.

Hollow core waveguides were made by defining the core with negative photoresist (SU-8), depositing the nano-wire layres and reinforcing the structure by burrying it with a bulk SiO₂ layer. After depositing the layers, the photoresist was etched of very carefully via acid bath. Optical properties of the waveguide, such as mode profile, confinement factor, loss etc was characterized.

Apart from rectangular waveguides, we also tried making "arch" shaped waveguides using re-flowed positive photoresist (AZ 2000 series + HMDS adhesion promoter) and acid based wet etching.

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