Thulium Doped Fiber Laser and Its Applications

Laser as one of the core components of the photonics industry plays a crucial role in keeping the compound annual growth rate (CAGR) of this industry much higher than the average of global GDP growth. The exceptional performance of fiber laser and its advantages, including robustness, excellent heat dissipation capability, compactness, high beam quality, free from alignment, low cost, etc. are the reasons that fiber laser shares about 50% of laser market revenue. The extensive applications of fiber lasers in industry, medicine, research, defense and other areas make them demanding for the future of our lives. Thulium doped fiber laser has been demonstrated to be able to operate from ultraviolet to mid infrared. The work presented in this dissertation, includes demonstration of single frequency blue laser fiber amplifier using thulium doped fiber; study of thulium doped fiber laser operating at 785 nm; investigation of 2 µm thulium doped fiber laser and magneto optical glasses for all fiber optical isolator and circulator in 2 µm region. In chapter 1, the performance of blue laser fiber amplifier was studied. A single frequency blue laser all-fiber amplifier was demonstrated for the first time. Over 150 mW continuous-wave single transverse-mode, and single longitudinal mode blue laser output was obtained with a 10-m 1000 ppm thulium-doped fluoride fiber pumped by a 1125 nm fiber laser at a power of 2 W. The output power was limited due to the onset of the competitive lasing at 784 nm. The concept of blue laser MOPA for underwater optical communication system was also demonstrated by using a GaN diode laser at 478 nm as the seed laser and a 7.5 m Tm3+-doped ZBLAN fiber amplifier as the power amplifier. A maximum output power of 235 mW was obtained. Photo-darkening and photo-curing of the thulium-doped fiber amplifier were also studied and analyzed. In chapter 2, all-fiber single-transverse-mode laser oscillators operating at 785 nm were demonstrated by splicing a 0.1