Volatile Organic Compound Sensor Based on PDMS Coated Fabry–Perot Interferometer With Vernier Effect

A novel volatile organic compound (VOC) sensor based on poly (dimethylsiloxane) (PDMS) coated Fabry-Perot interferometer (FPI) with Vernier effect was experimentally demonstrated. The proposed sensor, total length is ~1 mm, is composed of a segment of large mode area fiber (LMAF) and a segment of hollow-core fiber (HCF). The HCF and the LMAF form two Fabry-Perot cavities and achieve the Vernier effect. The proposed sensor head was coated with PDMS film so it is not affected by humidity. The high sensitivity of the proposed VOC sensor will be achieved by monitoring the interference spectral envelope of the cascaded FPI due to the Vernier effect, even the VOC sensor is short. The experimental results show that the sensitivity of isopropanol is 20 pm/ppm with the range from 0 to 500 ppm and the response time is ~50 s. The sensor has high sensitivity, waterproofness, and gas selectivity.