Observation of efficient Er 3+ : 4 I 11/2 → 4 I 13/2 transition in highly Er 3+ doped germanosilicate glass

Abstract Highly rare earth（RE）ions doped glass laser materials can produce efficient single frequency mid-infrared laser. In this work, a series germanosilicate glasses with various high erbium-doping concentration (up to 4 mol%) and without concentration quenching are fabricated. Spectroscopic properties and energy transfer (ET) mechanism of efficient Er 3+ : 4 I 11/2 → 4 I 13/2 transition have been investigated in detail upon a conventional 980 nm Laser Diode. The dense structure of silicate glass can be dissolved effectively by the introduction of GeO 2, which was analyzed by Raman spectra, so that the compatibility and luminous intensity of RE ions were improved. The high predicted spontaneous transition probability (A rad = 37.65 s −1 ) based on the Judd-Ofelt theory and large calculated emission cross section (8.8 × 10 −21 cm 2 ) are obtained. The above results indicate that these glasses are promising to be the single frequency mid-infrared laser material.