Michelson interferometer-based fiber-optic sensing of liquid refractive index

A fiber-optic sensor for liquid refractive index measurement based on a Michelson interferometer is described. The interferometer is achieved between the Fresnel reflections from the fiber ends of the coupler. The fiber ends are then in contact with the solvent and solution samples to provide reference and refractive index measurement, respectively. The refractive index of the solution is determined according to the fringe contrast of the interference fringes in the reflective spectrum of the sensor. Its ease of fabrication and low-cost offer the attractive applications in chemical and biological sensing.