Effective refractive index modulation based optical fiber humidity sensor employing etched fiber Bragg grating

Relative humidity (RH) sensor employing etched fiber Bragg grating (FBG) is reported where RH variations are captured using effective-index-modulation, rather than traditional strain-modulation. Additionely, linear sensor response over wide dynamic range with optimum characteristics is focused. Comprehensive experimental investigation is carried out for the sensor that comprises uniformly etched cladding in the FBG region. Obtained results are observed to be in agreement with the theoretical analysis. Sensor response is observed to be linear over dynamic range 3-94% RH with similar to 0.082 pm/%RH sensitivity, similar to 0.6%RH resolution, similar to +/- 2.5%RH accuracy, similar to +/- 0.2 pm average discrepancy and similar to 0.2s response time during humidification/desiccation.