Study On The Stability Of Er:YAG Solid State Laser Injection-locked Technology

Depending on keeping track of atmosphere wind field and grasping the data onatmosphere components in real time, the global climate change can be fore-castedaccurately and rapidly. Coherent Doppler wind-detecting radar, therefore, become hotspots of the relevant research, on account of their high detecting precision andsensitivity. Lasers at the wavelength of approximate1.6μm, have high safe threshold ofthe human eyes and strong reflection coefficient for aerosol particles, and thecorresponding photoelectric sensor is sensitive for such wavelength, which leads to theybeing the prime choice as the emission light source of laser radar. Narrow line-width,high beam quality, stable frequency and single frequency pulse output can be satisfiedby1.6μm injection-locking laser. Hence, this paper researched1.6μm injection-lockinglaser on both respects of theory and experiment.Theoretically, first, the theoretical model of quasi-four-level rate equations hasbeen established for continuous wave and Q-switched operation at room temperatureaccording to the transition mechanism of Er3+iron generating1.6μm laser. On the basisof the model, expressions of the slope efficiency, laser threshold and incident pumppower were achieved and the effect of output coupler transmittance and un-conversionfactor on output characteristics was analyzed, respectively. Furthermore, the stability ofEr:YAG solid state laser injection-locked technology, especially of the slave laser wasstudied. Injection-locking theoretical model was build on the classical theory of light-matter interaction. The numerical simulation estimated the influence of the injectedlaser strength, output coupler transmittance and resonator length on frequency detuning.Finally, factors on mode-coupling was discussed and mode-matching was analyzedtheoretically.Experimentally, the designs of single-longitudinal-mode-output master laser,high-power wide-line-width slave laser and frequency-locked servo control system meetthe requirements of each section of injection-locking laser. The master laser utilizedEr:YAG non-planar ring resonator and its single-longitudinal-mode output laser hadvertical polarization，the wavelength of1645.24nm and the maximum output power of530mW. The slave laser employed the resonator with bow-tie ring structure. Throughexperiments, the output characteristics was researched of the slave laser operating oncontinuous-wave mode and different repetition rates. Eventually，the stable injection-locking laser output was realized via “ramp hold fire” technology and the design ofinjection-coupling system and with pulse energy of2.9mJ, width of180ns, single-frequency-mode laser was achieved at the repetition rate of100Hz.