Wind turbines lubricant gearbox degradation detection by means of a lossy mode resonance based optical fiber refractometer

In this work, is presented the fabrication and characterization of optical fiber refractometer based on lossy mode resonances for turbine lubricant degradation. Three different optical fiber refractometers have been fabricated by means of the deposition of indium oxide thin-films. The sensitivity of the devices has been characterized as a function of the surrounding medium refractive index (from 1.332 to 1.471). Obtained results revealed that thinner coating possess higher sensitivities. These refractometers have been used to characterize the degradation of a synthetic industrial gearbox lubricant oil at working temperature.