Hollow Waveguides With Low Intrinsic Photoluminescence Fabricated With PECVD Silicon Nitride and Silicon Dioxide Films

A new type of integrated hollow core anti-resonant reflecting optical waveguide (ARROW) with low intrinsic photoluminescence (PL) fabricated with plasma-enhanced chemical vapor deposition (PECVD) silicon nitride (SiN) and silicon dioxide
$(\hbox{SiO}_{2})$
films is demonstrated. The waveguide is fabricated by surrounding the hollow core with alternating layers of SiN and
$\hbox{SiO}_{2}$
. The thicknesses and indices of the layers are designed to meet an anti-resonance condition. Compared to earlier ARROW structures made by depositing high-temperature (HT) SiN (250
$^{\circ}\hbox{C}$
), the PL background decreases by a factor of
$\sim$
10 when low-temperature (LT) SiN (100
$^{\circ}\hbox{C}$
) films are used. Therefore, LT SiN ARROWs are attractive platforms for sensitive fluorescence and Raman spectroscopy measurements of biomolecules.