Experimental Study On Single - Frequency Yb - Doped Fiber Laser And Its Main Oscillation Power Amplification

The properties of narrow linewidth, low noise and stable single-frequency (SF) lasers have much attention for its potential applications, such as optical fiber communication, optical fiber sensors, high resolution sensing and gravitational wave detector. Especially, the tunable SF lasers and high power SF laser with a master oscillator power amplifier show a very extensive and important application prospect. We designed1064nm and1083nm SF fiber laser with loop mirror filter (LMF) and polarization controller (PC). Then we changed the temperature of fiber Bragg grating (FBG) to tuned the wavelength of1064nm and1083nm SF fiber laser. At last, we use the SF fiber laser as the source to achieve master oscillator power amplifier (MOPA). The main contents of this thesis as follows:1. By the theory simulation of1064nm and1083nm SF fiber laser, we research the output power, which is effect on the fiber length and the doping concentration of fiber, the slope efficiency and threshold power as the change of fiber length, At last, we introduce the principle of the LMF and the measure method of narrow linewidth in SF fiber laser.2. We use LMF as the cavity mirror to research the experiment of1064nm and1083nm SF fiber laser. In the research, we change the reflection of FBG, the fiber length and the fiber length of saturable absorber (SA) in the LMF, which influence on the output power, the SF fiber laser result and the spectral characteristic. At last, we obtained the best reflection of the FBG is60%of1064nm SF fiber laser. In the experiments we achieved the output power of1064nm SF fiber laser is90.8mW at the pump power of300mW, the threshold power of pump power is40mW, the optical-optical efficiency is30.2%, corresponding the slop efficiency is40%and the instable of output power is2%. The best reflection of FBG is70%of1083nm SF fiber laser, the output power is46mW at the pump power of200mW, the threshold power of pump power is40mW as well, the optical-optical efficiency is23%, corresponding the slop efficiency is33.3%. We use20m single mode fiber as the delay line to measure the linewidth of SF fiber laser by the delay self-heterodyne, the result of linewidth is5kHz.3. On the basis of theory of the couple wave equation of FBG, we research the method how to relized the tuned wavelength of SF fiber laser by FBG:the strain effect on the FBG and the temperature influence on the FBG. We changed the temperature of FBG to achieve the wavelength change of SF fiber laser. From30℃to180℃, the wavelength of SF fiber laser changed from1063.3nm to1065.7nm, the tuned range is2.4nm. 4. From the theory of SF fiber amplifiers, we analysis the influence of factors on stimulated Brillouin scattering (SBS) in SF fiber amplifier. We use the SF fiber laser as the seed laser to research the experiment of MOPA SF fiber laser. In the experiment, we achieved1064nm SF fiber amplified power266mW, when the maximum pump power is400mW and input the seed power is6mW. The amplification rate is44.3times. The1083nm SF fiber amplified power254.6mW, when the maximum pump power is400mW and input the seed power is6mW. The amplification rate is42.4times.