Analytical modelization of a fiber optic-based surface plasmon resonance sensor

In this paper, the design of an optical sensor for water analysis based on the Surface Plasmon Resonance (SPR) technique is discussed, the sensor is a metal-coated optical fiber. An analytical model is developed to study the performance of the sensor by carrying out a comparative study between the different materials that the sensor parts are made of, in order to investigate how they affect the sensitivity and resonance visibility of the SPR sensor. The credibility of results is verified using the TMM method. Calculation results of the two methods agree reasonably well with each other, and show that a smaller refractive index contrast between the optical fiber material and the outer medium can remarkably enhance sensitivity, they also reveal that working with metals having lower plasma frequency can as well improve sensor performance. Results also suggest that the visibility of the plasmonic resonance is reduced for wavelength values where light absorption by water is important.