Research On Single-frequency High Power Tm-doped Fiber Laser Technology

The emission wavelength of Tm-doped fiber laser ranges from 1.7-2.1?m. Therefore, Tm-doped fiber laser has much application value in some fields such as biomedical, laser radar and remote sensing, new generation communication technology, industrial processing, middle and far infrared pumping, etc. The reports from worldwide indicate that, compared with 1?m-band, 2?m-band fiber laser has larger advantage and potential in high power output. Furthermore, single-frequency high power Tm-doped fiber laser has become one of the most important research directions in laser field. The research on single-frequency high power Tm-doped fiber laser can be considerably valuable. In this paper, we conduct a research on single-frequency high power Tm-doped fiber laser mainly for the purpose to obtain high power single-frequency output.At first, this paper introduces the features of Tm-doped fiber laser, demonstrates the huge potential in high power output, and also introduces the developing history and status of the Tm-doped fiber laser in terms of two perspectives: wide-spectrum and single-frequency.The optimizing of the theoretical model of SBS in high power single-frequency Tm-doped fiber amplifier is conducted. A simulation about the impacts of SBS effect was conducted based on the theoretical model of SBS in fiber laser. The factors such as pump power, signal power, fiber length, fiber diameter have been discussed in the simulation.The SBS features in 2?m-band single-frequency fiber laser have been researched by experiments. We summarized the method to suppress SBS effect from the experiments on suppression on stimulated Brillouin scattering in 2?m-band fiber laser based on phase modulation. And we found that ASE has a positive effect on SBS in passive fiber, but no obvious effect on SBS in fiber amplifier, from the experiment on the impact of ASE on SBS of 2?msingle-frequency signal. We also conducted a simulation about the impact of temperature gradient on SBS effect which indicated the temperature gradient had an effect on decrease integrated SBS gain and cause SBS shift.At last, we designed and built a single-frequency high power Tm-doped fiber laser employing MOPA structure. A series of test has been carried out. We obtained 220 W single –frequency output power. The center wavelength is 1970.69 nm and the linewidth is less than 3GHz. The slope efficiency is about 56%. It is indicated that higher output power is hopefully to be achieved if more pump power is employed to the main amplifier.