Study on highly sensitive asymmetric waveguide optical sensor for detection of sucrose concentration based on leaky quasi-modes

The development of a highly sensitive asymmetric planar waveguide optical sensor based on a mathematical model using leaky quasi-modes in an endeavor to measure slight changes of aqueous sucrose concentration is presented in this paper. The planar waveguide sensor has been fabricated using Silicon Oxynitride (SiON) based material with standard fabrication process such as Plasma Enhanced Chemical Vapor Deposition (PECVD) and Reactive Ion Etching (RIE) techniques. The propagation constant of fundamental modes for TE mode of the waveguide geometry have been estimated using Simple Effective Index Method (SEIM) based on sinusoidal modes. The technique is based on Evanescent Wave Sensing (EWS) scheme, inducing an effective refractive index change. The merits of this sensor are simplicity, highly sensitivity, screening the potential that it can be used for online monitoring of blood glucose levels in the near future. The sensitivity of the waveguide is ~10 times more than that of the previously reported work on planar waveguide sensors and the results obtained experimentally matches well with the obtained theoretical result.