Fiber-Optic Thermometer Using Thermal Radiation and Thermally Excited Luminescence

Thermally excited visible light luminescence is observed from SiO
₂
glass doped with rare-earth elements. Thermal radiation similar to the black body radiation was observed in the SiO
₂
doped with Sc, Y, La, Ce, Pr, Eu, Tb, Lu, Gd, Sm. Peak intensities of radiations from these sensor materials increase sensitively with temperature. Intensity ratio at different wavelengths is found to be suitable for the temperature measurement. Thermal activation energy of these elements is relatively larger than those of thermally excited f-f transitions seen in Er, Tm, Ho, Nd, Yb and Dy doped SiO
₂
. Thermal radiation from rare-earth doped SiO
₂
is potentially applicable as a sensor material in the fiber-optic thermal radiation thermometer