Integrated optical refractometer based on bend waveguide with air trench structure

Abstract

This study proposes an optical sensor based on a refractometer integrating a bend waveguide and a trench structure. The optical sensor is a planar lightwave circuit device involving a bend waveguide with maximum optical loss. A trench structure was aligned with the partially exposed core layer’s sidewall of the bend waveguide, providing a quantitative measurement condition. The insertion losses of the proposed 1×2 single-mode optical splitter-type sensor were 4.38 and 8.67 dB for the reference waveguide and sensing waveguide, respectively, at a wavelength of 1550 nm. The optical loss of the sensing waveguide depends on the change in the refractive index of the material in contact with the trench, but the reference waveguide had stable optical propagating characteristics regardless of the variations of the refractive index.