Erbium-Doped Tellurite Glass Microlaser in C-Band and L-Band

We report results of experimental laser generation in an Er-doped tellurite glass microsphere under in-band pumping. Depending on settings, single-mode and multimode lasing is achieved in the C-band near 1.56 μm and in the L-band near 1.60 μm, as well as simultaneously in both bands. We demonstrate stable single-mode L-band generation at 1.599 μm with the standard deviation of the output power <; 0.5%. We also present a simple yet efficient analytical model to describe lasing for better understanding of the observed regimes and further control and optimization of such systems. We found theoretically that for low Q-factors lasing occurs in the C-band but for relatively high Q-factors lasing occurs in the L-band, which agrees with the experimental observations. Switching between the generated wavelengths from the C-band to the L-band occurs with a jump which was observed experimentally and explained theoretically. We show numerically that the lasing threshold is determined by both the Q-factor and the diameter of the microsphere. The obtained results can speed-up progress in the development of tellurite glass microlasers in the telecommunication range and give a better understanding of their theoretical aspects.