Numerical Study of Sensitivity Enhancement in Optical Waveguide Sensor Due to Core Diameter

The need for sensing technology has arisen as a result of the growing environmental concern over microplastic pollution in water systems. In this work, a potential microplastic sensor based on an optical planar doped polymer waveguide was theoretically investigated by using Wave Optics Module-COMSOL Multiphysics® software over a range of 2 μm to 16 μm waveguide core diameters. The microplastic refractive index of the analytes employed in this research ranged from 1.48 RIU to 1.50 RIU reflecting the microplastic refractive index. The results revealed that a 2 μm core diameter of the waveguide sensor achieved the best sensitivity value of 5.12 × 10–5 at fixed cladding depth and wavelength of 0 μm and 617 nm, respectively. The simulation work offers useful information for designing a potential waveguide for real world applications to detect microplastics in water. This study is believed to contribute towards the development of cutting-edge sensing technologies through the optimized optical waveguide sensor design, which shows promise in addressing the serious problem of microplastic pollution in water systems.