Temperature-dependent fluorescence characteristics of an ytterbium-sensitized erbium-doped silica fiber for sensor applications

The characteristics of temperature-dependent fluorescence of an ytterbium (Yb3+)-sensitized erbium (Er3+)-doped silica fiber are presented. A 10-cm long double-clad Yb3+/Er3+-codoped fiber is diode-pumped at 915 nm and the individual fluorescence intensities from Yb3+ and Er3+ ions are measured with varying the fiber temperature. The ratio of the dual fluorescence intensities varies exponentially with temperature in the range of room temperature to ∼300 °C. This dual-dopant system has dual emission bands that emit comparable fluorescence powers. Particularly, the self-referencing fluorescence intensity ratio is insensitive to external perturbations in the fiber, which is useful for sensors that are used in a harsh environment without any use of additional referencing techniques. This scheme allows a compact, long-life, and low-cost temperature sensor and can also be combined with a wide range of existing fiber-optic multiplexing schemes that can simultaneously detect multiple physical parameters.