Integrated optical sensor using a liquid-core waveguide in a Mach-Zehnder interferometer.

We demonstrate experimentally an optical sensor based on a monolithically integrated Mach-Zehnder interferometer comprising a liquid-core waveguide in one of the optical paths. The device is fabricated with a technique for self-forming microchannels in silica-on-silicon using standard photolithography and deposition processes. Refractometry with a resolution of better than 4x10(-6) is demonstrated using the thermo-optic effect of the liquid medium to vary its refractive index.

Monolithic integration of microfluidic channels, liquid-core waveguides, and silica waveguides on silicon.

The fabrication of embedded microchannels monolithically integrated with optical waveguides by plasma-enhanced chemical vapor deposition of doped silica glass is reported. Both waveguide ridges and template ridges for microchannel formation are patterned in a single photolithography step. The microchannels are formed within an overlay of borophosphosilicate glass (BPSG), which also serves as the top cladding layer of the silica waveguides.