The codoping of a heavy-metal fluoride glass by two rare-earth ions, erbium and ytterbium, permits the semiconductor laser infrared excitation of two visible neighboring fluorescence lines of erbium by upconversion, the intensity ratio of which is a single variable function of temperature.
© 1990 Optical Society of America
Original Manuscript: March 13, 1990
Manuscript Accepted: June 15, 1990
Published: October 1, 1990
H. Berthou and C. K. Jörgensen, "Optical-fiber temperature sensor based on upconversion-excited fluorescence," Opt. Lett. 15, 1100-1102 (1990)