Abstract

An optical fiber humidity sensor with a microfiber knot resonator (MKR) nested U-shaped Mach-Zehnder (MZ) interferometer based on the Vernier effect is proposed. While the reference arm is protected by cured ultraviolet glue, the sensing arm is coated by agarose. The Vernier effect is realized by superimposing the comb-like transmission spectra of the MKR and MZ interfernce, which are designed to have slightly different free spectral ranges. Experimental results indicate that the proposed sensor can provide a maximum humidity sensitivity of 2.442 nm/%RH with a measurement range from 60% RH to 95% RH. The sensor temperature response, reversibility and repeatability are also investigated. The response time is found to be 102 ms for a change of ∼30% RH. This sensor not only retains key features and merits of the MKR, including low cost and small footprint, but also has a simpler preparation process compared with conventional sensors based on the Vernier effect.

Experimental demonstration of a high-sensitivity humidity sensor based on an Agarose-coated transmission-type photonic crystal fiber interferometer

Jinesh Mathew, Yuliya Semenova, and Gerald Farrell
Appl. Opt. 52(16) 3884-3890 (2013)

Effect of coating thickness on the sensitivity of a humidity sensor based on an Agarose coated photonic crystal fiber interferometer

Jinesh Mathew, Yuliya Semenova, and Gerald Farrell
Opt. Express 21(5) 6313-6320 (2013)

Agarose coated spherical micro resonator for humidity measurements

Arun Kumar Mallik, Dejun Liu, Vishnu Kavungal, Qiang Wu, Gerald Farrell, and Yuliya Semenova
Opt. Express 24(19) 21216-21227 (2016)

Study of the influence of the agarose hydrogel layer thickness on sensitivity of the coated silica microsphere resonator to humidity

Arun Kumar Mallik, Gerald Farrell, Qiang Wu, and Yuliya Semenova
Appl. Opt. 56(14) 4065-4069 (2017)

Humidity and temperature sensor based on a Mach–Zehnder interferometer with a pokal taper and peanut taper

Yimei Zhong, Zhengrong Tong, Weihua Zhang, Juan Qin, and Wenlin Gao
Appl. Opt. 58(29) 7981-7986 (2019)