Thulium Doped Microsphere Laser and Fiber Laser

by Wu, Jianfeng.

In this dissertation, the spectroscopic properties of thulium doped tellurite and thulium doped germanate glass are characterized. Absorption and emission spectra, lifetime, Fourier Transform Infrared Spectroscopy (FTIR), and thermo-gravimetric analysis are utilized to characterize the thulium doped tellurite bulk glass samples. Judd- Oflet theory, Fuchtbauer-ladenburg theory, Kushida’s model, Burshtein’s hopping model, Miyakawa’s non-resonant energy transfer model are employed in ab-initio calculation of cross relaxation energy transfer. The fundamental mechanism of cross relaxation energy transfer is examined through ab-initio calculation and self-calibrating spectroscopy. Thulium doped tellurite glass microspheres are fabricated by spin casting technique. Single mode 2-mm laser is demonstrated from tellurite microsphere with high thulium doping concentration. General laser condition for self-terminating transition is discussed and concluded. Demonstration of 1.5-mm laser is achieved from a self-terminating transition of thulium doped in tellurite microsphere through a cooperative lasing technique. Highly efficient 1.9 micron fiber laser is demonstrated in thulium doped germanate fiber laser. The slope efficiency of the fiber laser is 58%, which indicates a quantum efficiency of 1.79. Single frequency laser operation at 1.9 micron has been successfully accomplished. A fiber based Fabry-Perot interferometer is utilized as a scanning filter to examine the single frequency operation. 4 W laser output has been achieved from a 40 cm long Tm-doped germanate double cladding fiber laser. 13