Simultaneous measurement of surrounding temperature and refractive index by the tilted fiber Bragg grating

Simultaneous independent measurement of surrounding refractive index (SRI) and temperature using the tilted fiber Bragg grating is proposed and experimentally demonstrated. Core mode is sensitive only to the temperature while cladding modes are sensitive to the temperature and SRI, theirs temperature sensitivities are equal. The wavelength shifts of two kinds of modes with a change of temperature and SRI allow for simultaneous discrimination temperature and SRI effect. In addition, the sensitivity of TFBG to SRI is significantly enhanced by hydrofluoric etching clad; it can satisfy the custom-built sensitivity that the clad of TFBG was etched in different degrees as well. This sensor is potential for chemical-biochemical sensing application and measuring the concentration of the chemical solutions accurately.

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