| The laser of 2 ?m waveband has become one of the main sources of wind Lidar due to locate in atmospheric window and safe to human eye.The output laser of emission source should be characterized by narrow linewidth,long pulse and high power,so as to achieve the high precision and long-range detection for the Doppler Coherent Lidar.The transmitting source satisfying the requirements of the radar system could be constructed by injection-locking technology based on the narrow linewidth characteristic of the main laser and the characteristics of long pulse and high power of the slave laser.The pulse width of output laser is directly related to the length of the resonator for the slave laser.The fiber ring laser can be used as a slave laser for long pulse output in the injection-locking laser due to long-distance flexible transmission for the laser in fiber.In this dissertation,a single longitudinal mode laser which based on the structure of the standing wave cavity is used as main laser and a fiber ring laser which based on space coupling structure is used as a slave laser to carry out the research on 2 ?m injection of thulium-doped fiber ring laser(TDFRL).The research on 2 ?m band Ho-doped single longitudinal mode(SLM)lasers are carried out.A Tm,Ho:YAG SLM laser is constructed by using the twisted mode technology.Output power of 106 m W SLM laser at the wavelength of 2090.4 nm is achieved;Ho single-doped SLM laser is constructed through more compact standing wave cavity for Ho single-doped laser.The output power of 309 m W SLM laser is obtained at the wavelength of 2081.2 nm for Ho:YAG SLM laser;The output power of 264 m W SLM laser is obtained at the wavelength of 2100.7 nm for Ho:Lu AG SLM laser;The output power of 330 m W SLM laser is obtained at the wavelength of 2050.7 nm for Ho:YLF SLM laser.An actively Q-switched fiber ring laser is constructed through space coupling to meet the requirements of high power and long pulse of slave laser in the injectionlocking laser system.In theory,the rate equations of the TDFRL in CW and Qswitching operation are established.The influence of various parameters on the output performance of the laser is analyzed by numerical solution of rate equations.For CW operation of TDFRL,the longitudinal distribution of the pump power and the oscillating optical power in the gain fiber are studied.In additon,the influence of active fiber length and output mirror transmittance on laser are analyzed.For Qswitching operation,the pulse width effected by pump power,the transmittance of output mirror and length of resonator is studied and analyzed.In experiment,the laser output performance of TDFRL is studied experimentally under CW and Q-switching operation.The output performance under variation of active fiber length and output mirror transmittance are studied experimentally for CW operation.The working mechanism of the AO Q-switch in the TDFRL is studied and analyzed for Q-switching operation,and the output performance of the TDFRL is further experimentally studied.Up to 150 ?J with pulse width of 207 ns at a repetition rate of 100 Hz was achieved for the cavity optical length of 6.68 m.The pulse width was 382 ns while the cavity optical length increasing to 12 m under same output pulse energy,.Finally,the output characteristics of TDFRL under continuous and pulse conditions are studied and analyzed by injecting the seed light into the TDFRL with the SLM laser output from the Ho:YAG laser and Ho:YLF laser. |
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