Spectral properties of ultra-low thermal expansion Er3+/Yb3+ co-doped phosphate glasses.

An Er3+/Yb3+ co-doped phosphate glass with an ultra-low thermal expansion coefficient (55 × 10−7 K−1) was developed. The EYAP5 glass (80Al(PO 3) 3 –20AlF 3 -1.5Er 2 O 3 -7.5Yb 2 O 3 , mol%) exhibits excellent spectral properties, thermomechanical properties, and chemical durability. Compared with traditional high phosphorus-doped silica glasses, EYAP5 glass achieves a higher Er3+/Yb3+ doping concentration and energy transfer efficiency from Yb3+ to Er3+ ions. Meanwhile, the absorption spectra, emission spectra, and fluorescence decay were systematically measured and compared in the temperature range of 300–480 K. Unlike the cases at 915 and 974 nm, the absorption cross section at 940 nm (∼0.21 pm2) has the highest temperature stability, which facilitates the stable operation of the 1.5 μm high-average-power laser. Furthermore, the temperature rises increase the energy transfer efficiency from Yb3+ to Er3+ ions, effectively suppressing the amplified spontaneous emission (ASE) at ∼1 μm. [ABSTRACT FROM AUTHOR]