Optical fiber liquid-level sensor using a surface plasmon resonance

摘要

A liquid-level optical fiber sensor based on refractive index sensitivity of surface plasmon resonance has been proposed and demonstrated. The sensor can continuously measure a wide distance range in the liquids with a single fiber element, since the sensing interface is characterized on the fiber-cladding surface. The fiber element, having the gold film thickness of 70nm on the sensing surface, shows the capability for the use of refractive index to be sensed ranged from 1.333 to 1.428 RIU. The sensitivity has been experimentally achieved to be 2.86% change of the input light intensity per millimeter for the 40mm measurement range.