PDMS-coated no-core fiber interferometer with enhanced sensitivity for temperature monitoring applications

This study proposed a PDMS-coated no-core fiber interferometer for temperature monitoring. The fiber optic interferometer is based on a cascaded structure of single-mode fiber-no-core fiber-single-mode fiber (SMF-NCF-SMF), and a PDMS layer is coated onto the interferometer surface to perform as the adhesive packaging layer. When compared with the pure silica fiber interferometer, the coated PDMS owns excellent thermal performances, resulting in a dramatic sensitivity improvement of temperature. Besides, since the fiber structure itself is fragile, the coated PDMS can also protect the sensor structure, which improves its reliability for practical applications. The experimental results verify that the proposed low-cost PDMS-coated fiber interferometer owns high sensitivity (200.2 pm/degrees C) for temperature measurement. It shows excellent consistency and repeatability within the thermal cycles from 40 degrees C to 80 degrees C. Thus, it is considered as a promising candidate to fabricate the fiber optic smart structure for temperature health monitoring applications.