Waveguide-mode Sensor Chip with Si/SiO2/SiOx Structure

A waveguide-mode sensor detects changes in the complex refractive index on the surface of a planar waveguide chip with high sensitivity. We developed a waveguide-mode sensor chip with the Si/SiO2 structure. It was predicted from simulations that a third layer of high refractive index added to the outermost surface of the planar waveguide may improve the sensitivity of the waveguide-mode sensor. In this research, we designed and manufactured a borosilicate glass substrate chip with a Si/SiO2/SiOx structure via sputtering deposition, and we improved the sensitivity of the waveguide-mode sensor chip. The Si/SiO2/SiOx structure chip was approximately 1.5 times more sensitive to refractive index changes than the Si/SiO2 structure chip.