Novel TiO₂–GO Nanocomposite-Based Ultrahigh Sensitive Optical Fiber Humidity Sensor

The main objective of the present research is to develop an optical fiber relative humidity (RH) sensor having ultrahigh sensitivity, linear response over a wide dynamic range, as well as optimum response/recovery times while utilizing the simple optical fiber sensing configuration. The proposed sensor, developed to achieve these objectives, exploits the phenomena of intensity modulation via evanescent wave absorption in the sensing region, which is designed by employing TiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>–GO nanocomposite-doped silica sol–gel nanostructured thin sensing film onto a short centrally decladded region of a plastic-clad silica fiber. Detailed experimental investigations are carried out to analyze the response characteristics of the proposed sensor. The developed sensor is characterized by a significantly enhanced sensitivity of 0.0094 RH<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> while responding linearly over a large dynamic range of 9%−92% RH. In addition, the sensor exhibits a high degree of reversibility, repeatability, reliability, and fast response and recovery time.