Variation of Er3+ cross section for stimulated emission with glass composition

The absorption and fluorescence spectrum in the region of 6500 cm−1 (1·54 μm) due to trivalent erbium has been studied in a wide range of silicate, phosphate and borate glasses. Representative spectra have been used to determine the cross section for stimulated emission and relative gain coefficient as a function of frequency. The frequency at which laser emission could occur was determined for various levels of excitation by allowing for absorption losses, and the gain coefficients at these frequencies were compared for different glasses. Within the ranges of glass studied a high integrated absorption cross section generally led to a high gain coefficient. Values of the cross section for stimulated emission of Er3+ are lower than for Nd3+ at 1·6 μm by about an order of magnitude.