Vernier Effect-Based Optical Fiber Sensor for Humidity and Temperature Monitoring

We report on a simple and cost-effective sensing scheme for humidity and temperature sensing, based on the generation of optical Vernier effect using two different fiber optic Fabry-Perot interferometers (FFPIs). By using an insensitive reference FFPI (rFFPI) and a sensitive FFPI (sFFPI) fabricated by hot and cold splicing methods, respectively, the complexity associated with the inherent traditional isolation schemes was mitigated, allowing to attain the maximum sensitivities of -2.69 nm/°C and -2.4 nm/% for temperature and relative humidity, respectively. The sensor's performance combined with its simple and customizable configuration makes it a suitable option for applications with high-resolution requirements.