Abstract

An integrated-optic, evanescent-wave biosensor utilizing a multimode interferometric waveguide based on a Si₃N₄ rib-optical waveguide consisting of the Si/SiO₂/Si₃N₄/SiO₂ stacked structure was described. It has been confirmed that the very fine changes in the refractive index of an analyte greatly affect the location of interferometric mode patterns and ultimately output optical power, and proved that this principle could be applied to integrated-optic biosensors. The sensitivity for the lengths of the multimode interferers 5380, 5400, and 5420μm, respectively was calculated from 6.714 to 7.63 [au/RIU] for the refractive index range of 1.33 to 1.35.

© 2021 The Author(s)