Versatile luminescence thermometry via intense green defect emission from an infrared-pumped fluorosilicate optical fiber

An all-glass optical fiber capable of two distinct methods of optical thermometry is described. Specifically, a silica-clad, barium fluorosilicate glass core fiber, when pumped in the infrared, exhibits visibly intense green defect luminescence whose intensity and upper-state lifetime are strong functions of temperature. Intensity-based optical thermometry over the range from 25^◦C to 130^◦C is demonstrated, while a lifetime-based temperature sensitivity is shown from 25^◦C to 100^◦C. Time-domain measurements yield a relative sensitivity of 2.85% K⁻¹ at 373 K (100^◦C). A proof-of-concept distributed sensor system using a commercial digital single-lens reflex camera is presented, resulting in a measured maximum relative sensitivity of 1.13% K⁻¹ at 368 K (95^◦C). The sensing system described herein stands as a new blueprint for defect-based luminescence thermometry that takes advantage of pre-existing and relatively inexpensive optical components, and allows for the use of standard cameras or simply direct human observation.