Relative Humidity Measurement Based on a Tapered, PVA-Coated Fiber Optics Multimode Interference Sensor

Abstract

A relative humidity (RH) fiber optic sensor is demonstrated based on the multimode interference (MMI) phenomenon utilizing a no-core fiber (NCF) coated with polyvinyl alcohol (PVA). The sensor’s structure is simple and consists of a section of NCF spliced between two standard single-mode fibers (SMFs). The fabrication and testing of a tapered version with enhanced sensitivity is also presented. The native MMI sensor showed a sensitivity of 5.6nm/RH%, in the range from 87 RH% to 93 RH%, while the tapered one exhibited an increased sensitivity of 6.6nm/RH%, in the range from 91.5 RH% to 94 RH%. The sensitivity values obtained with these MMI sensors are at least twice as large as the most sensitive fiber optics humidity sensor reported in the literature in a similar RH range.

The Structure and Applications of Fused Tapered Fiber Optic Sensing: A Review

“…Li et al [125 terferometric sensor using an SMF-PCF-SMF structure, achieving humid through the fusion of tapered coupling and graphene coating. Within a h 36.0% RH to 75.3% RH, the sensor exhibited high sensitivity, reaching 3 Quiñones-Flores et al [126] designed a relative humidity (RH) sensor ba mode interference (MMI) phenomenon using a coreless optical fiber (N…”

“…Within a humidity range of 36.0% RH to 75.3% RH, the sensor exhibited high sensitivity, reaching 340.13 pm/% RH. Quiñones-Flores et al [126] designed a relative humidity (RH) sensor based on the multimode interference (MMI) phenomenon using a coreless optical fiber (NCF) coated with polyvinyl alcohol (PVA), as shown in Figure 22. The sensor consisted of a segment of NCF spliced between two single-mode fibers (SMFs).…”