Fluorescence intensity ratio technique for optical fiber point temperature sensing

Abstract

The fluorescence intensity ratio technique for optical fiber-based point temperature sensing is reviewed, including the materials suitable for this technique. The temperature dependence of the fluorescence intensity ratio has been studied using thermally coupled energy levels in seven different rare earth ions doped into a variety of glasses and crystals. Sensor prototypes developed using Pr3+:ZBLANP, Nd3+-doped silica fiber and Yb3+-doped silica fiber as the sensing material have been used to measure temperatures covering the range of approximately −50 to 600 °C with a resolution of the order of 1 °C.

NIR-to-visible and NIR-to-NIR upconversion in lanthanide doped nanocrystalline GdOF with trigonal structure

“…This heating will induce a population increase of the 2 H 11/2 higher lying level and therefore a stronger emission intensity. This behavior is well-known and it was already observed for other Yb 3+ /Er 3+ doped nanocrystalline samples [22][23][24]. The Stark level structure of the emission transitions is clearly evident, indicating that inhomogeneous broadening is not very important in determining the width of the emission bands.…”

Multiple temperature effects on up-conversion fluorescences of Er3+-Y b3+-Mo6+ codoped TiO2 and high thermal sensitivity

“…Up-conversion emission of rare earth ions doped materials is a popular approach to realize FIR measurement due to large amount of coupled energy levels in several rare earth ions and the easily accessible up-conversion fluorescence with near-infrared radiation from low-cost commercially available diodes. [1][2][3][4][5] However, lower up-conversion efficiency and small FIR value can reduce effective sensitivity and accuracy of sensing behavior and limit potential application in optical thermal sensors.…”

“…[1][2][3][4][5][6] FIR technique is applied to a fluorescent system in which two closely spaced energy levels, with separations of the order of thermal energy, are involved following a Boltzmann-type population distribution. Up-conversion emission of rare earth ions doped materials is a popular approach to realize FIR measurement due to large amount of coupled energy levels in several rare earth ions and the easily accessible up-conversion fluorescence with near-infrared radiation from low-cost commercially available diodes.…”

(Y0.968Er0.002Yb0.030) 2 O3 Upconverting Particles as Optical Heater

“…The temperature sensing performance of some rare earth doped upconverting materials have been studied recently [6][7][8]. The temperature dependent fluorescence intensity ratio (FIR) of two closely lying energy levels (thermally coupled) of a rare earth ion is studied at different temperatures [7][8][9][10][11]. The technique also includes the variation of FIR of the Stark sublevels in single rare earth ion and two closely lying levels of different rare earth ions [12,13].…”