Absorption-Modulated Crossed-Optical Fiber-Sensor Platform for Measurements in Liquid Environments and Flow Streams

A new evanescent-wave fiber sensor is described that utilizes absorption-modulated luminescence (aml) in combination with a crossed-fiber sensor platform. the luminescence signals of two crossed-fiber reference regions,placed on opposite sides of the stretch of fiber supporting the absorbance sensor,monitor the optical intensity in the fiber core. evanescent absorption of the sensor reduces a portion of the excitation light and modulates the luminescence of the second reference region. the attenuation is determined from the luminescence intensity of both reference regions similar to the beer-lambert law. the aml-crossed-fiber technique was demonstrated using the absorbance of the zn(ii)-pan2 complex at 555 nm. a linear response was obtained over a zinc(ii) concentration range of 0 to 20 μm (approximately 0 to 1.3 ppm). a nonlinear response was observed at higher zinc(ii) concentrations and was attributed to depletion of higher-order modes in the fiber. this was corroborated by the measured induced repopulation of these modes. © 2017 paul e. henning and peter geissinger.