Design of integrated refractive index sensor based on bend waveguide with a trench structure

This study proposes a novel optical sensor structure based on a refractometer integrating a bend waveguide and an air trench. The optical sensor consists of a U-bend waveguide connecting four C-bends and a trench structure to expose the partial core layer. The U-bend waveguide consists of one C-bend with the maximum optical loss and three C-bend with minimum losses. A trench provides a quantitative measurement environment, and is aligned with the sidewall of a C-bend having the maximum loss. The intensity of the output power is dependent on the change of refractive index of the measured material.