Hollow waveguides with low intrinsic photoluminescence fabricated with $Ta2O5$ and $SiO2$ films

A type of integrated hollow core waveguide with low intrinsic photoluminescence fabricated with $Ta2O5$ and $SiO2$ films is demonstrated. Hollow core waveguides made with a combination of plasma-enhanced chemical vapor deposition $SiO2$ and sputtered $Ta2O5$ provide a nearly optimal structure for optofluidic biofluorescence measurements with low optical loss, high fabrication yield, and low background photoluminescence. Compared to earlier structures made using $Si3N4$⁠, the photoluminescence background of $Ta2O5$ based hollow core waveguides is decreased by a factor of 10 and the signal-to-noise ratio for fluorescent nanobead detection is improved by a factor of 12.