Highly doped Tm3+ tellurite glasses for 2 µm laser source

The development of stable single frequency fiber laser requires the use of short cavity length and therefore high gain per unit length medium. Tellurite glasses possess the suitable properties to realize such a device that would operate in the 2 mum wavelength region. Amongst those properties are low phonon energy and high rare earth ion solubility. The optical and thermo-mechanical properties of a series of tellurite glasses (75 mol%TeO₂.20 mol%ZnO-5 mol%Na₂O) highly doped with Tm³⁺ ions (up to 111,564 ppm) are presented and discussed. The results presented suggest an optimum concentration in Tm³⁺ of about 60,000 ppm to be used as fiber core material. An adequate glass composition for fiber cladding is also proposed.