An experimental and theoretical investigation of a 2 μm wavelength low-threshold microsphere laser

We present our results on an experimental and theoretical investigation into a glass microsphere laser emitting at 2 μm wavelength. First, we fabricated Ho3+-doped tellurite glass fiber and measured the absorption and emission spectra, and the fluorescence lifetime. Using this fiber, a tellurite glass microsphere with a Q-factor of 2×106 was also prepared and a single-mode laser output with a low threshold of 342 μW was observed using a 1150 nm laser as the pump source. The dynamic characteristics of the microsphere laser were studied theoretically by considering Rare-earth ion spectroscopy, the rate equation of the rare-earth energy level, and the light-matter interactions in the microsphere. This work can be used to study laser emission with low threshold in rare earth doped compound glass microresonator for a wide range of applications, such as gas sensing, integrated photonics and medical surgery.