LMR-based optical fiber refractometers for oil degradation sensing applications in synthetic lubricant oils

In this work, is presented the fabrication and characterization of optical fiber refractometer based on the lossy mode resonances (LMR). Indium-tin-oxide and tin dioxide thin films deposited on optical fibers are used as the LMR supporting coatings. These resonances shift to the red as a function of the external refractive index. The refractometer has been used to characterize the degradation of a synthetic industrial gear lubricant oil at working temperature.