Net Optical Gain Coefficients of Cu and Tm Single-Doped and Co-Doped Germanate Glasses.

Broadband tunable solid-state lasers continue to present challenges to scientists today. The gain medium is significant for realizing broadband tunable solid-state lasers. In this investigation, the optical gain performance for Tm and Cu single-doped and co-doped germanate glasses with broadband emissions was studied via an amplified spontaneous emission (ASE) technique. It was found that the net optical gain coefficients (NOGCs) of Tm single-doped glass were larger than those for Cu single-doped glass. When Tm was introduced, the emission broadband width of Cu-doped glass was effectively extended. Moreover, it was found that for the co-doped glass the NOGCs at the wavelengths for Tm and Cu emissions were larger than those of Tm and Cu single-doped glasses at the same wavelengths. In addition, the NOGC values of Tm and Cu co-doped germanate glasses were of the same order of magnitude, and were maintained in a stable range at different wavelengths. These results indicate that the Tm and Cu co-doped glasses studied may be a good candidate medium for broadband tunable solid-state lasers.