Optical fiber humidity sensor with C60-THAM as molecule receptors

Abstract

This study proposed a high sensitivity optical fiber relative humidity sensor (OFHS). Besides, a fullerene derivative, C 60 -THAM, was synthesized and firstly reported as a molecule receptor in the OFHS. Compared with the widely researched carbon-based materials in OFHS, the C 60 -THAM film has abundant amino dangling bonds, hence emerges naturally as excellent receptors for water molecules. Besides, a cascaded Fabry-Perot interferometer (FPI) was fabricated in the core of single-mode fiber (SMF) without surface damage by femtosecond laser. In the OFHS, the relative humidity (RH) was measured by the Vernier effect. The working principle of the OFHS was analyzed through calculation and simulation. In the experiment, C 60 -THAM was coated on the plant fiber end. The sensitivity of the sensor is about 0.42 nm/RH as the relative humidity change from 30% to 65% while the optical-matter reaction length is only about 150 nm. Moreover, the sensor exhibited a stable performance as the RH was decreasing from 65% to 30%. The OFHS in this work is fast response and the response time for the rising and decay process was about 2.2 s and 3.2 s respectively. • A fullerene derivative, C 60 -THAM, was synthesized and its application in the fiber humidity sensor was researched. • The humidity sensor is fast response and the rising and decay time is about 2.2 s and 3.2 s respecitively. • The sensitivity is 0.42 nm/RH as the humidity change from 30% to 65% while the optical-matter reaction length is 150 nm.