Yoh IMAI and Takaaki HOKAZONO

Department of Computer Science and Electronics Kyushu Institute of Technology, 680-4, Kawazu, Iizuka-shi, Fukuoka-ken, 820 Japan

(Received July 2, 1996; Accepted September 12, 1996)

Temperature sensing using 1.54 μm fluorescence at the transition between the energy levels ⁴I_15/2 (ground state) and ⁴I_13/2 generated in an erbium-doped fiber with 1.48 μm pumping is proposed. The fluorescence has a peculiar spectral profile that possesses two peaks around 1.530 μm and 1.552 μm wavelengths. The temperature-dependent fluorescence is investigated in the temperature range between -50°C and 90°C. The power ratio between the two peaks increases with an increase in temperature. The sensitivity of the ratio is 0.007/°C on average in the measured temperature range. The total fluorescence power and the absorption loss at λ=1480 nm in the fiber decrease as the temperature increases. Optical fiber temperature sensing immune from the fluctuation in pumping power can be performed using the peak power ratio and/or the absorption loss.

Key words : optical fiber sensor, temperature sensing erbium-doped fiber, fluorescence spectrum, transition absorption, peak power ratio, absorption loss, photoluminescence