Study On Diode-end-Pumped All-solid-state CW Blue Laser At 473nm

LD pumped blue laser has many advantages, such as compact configuration, short wavelength, high efficiency, long life-span and high stability, so, it has broad applications in information storage, multicolor display, underwater communication & detector, laser refrigeration, biomedicine and entertainment field. But, the industrialization of watt-level LD pumped all-solid-state blue laser lag behind, which confines its applications.The Elements that constitute blue laser such as pumping source, laser crystal, frequency-doubling crystal and cooling system were introduced; the whole project such as cavity design, optical lens coating, mode matching, beam quality, blue problems were analyzed.Begin with quasi-three-level rate equation, the expression of threshhold and interior & exterior slope efficiency were numerical calculated and simulated; Based on coupling equation of frequency-doubling light-wave, efficiency equation of frequency-doubling was given, the principle of phase matching and parameters which influence frequency-doubling efficiency were discussed. Nd:YAG which is propitious to industrialization was selected as laser crystal and BIBO was selected as frequency-doubling crystal after the several common crystals was carefully compared and investigated.In order to find reasonable resonators, the parameters of three-folded-cavity were calculated by using the ABCD ray matrix methords and parameter g. Under the consideration of thermal lens effect, the numerical value of thermal lens focus versus the maximal pump power in the experiments was calculated. Especially, emperature field and thermal lens effects of laser diode end pumped quadrate composite Nd:YAG rod were investigated through numerical analysis methods. Firstly, a linear resonator was set up. With the use of the ordinary homemade Nd:YAG/BIBO crystal which cooled by TEC, 220mW blue laser at 473nm with respect to the incident pump power of 3W was obtained. The optical conversion efficient was up to 7.3%. Secondly, a three-folded-cavity resonator that is insensitive to thermal effect was designed. A maximal output power of 710 mW at 473nm was obtained with the incident pump power of 18W. Thirdly, a four-folded-cavity resonator that is insensitive to thermal effect was under the experiments. With the use of compound Nd:YAG crystal, a maximal output power of 3.53W at 946nm was obtained with the incident pump power of 18.5W. The laser beam parameters of three & four-folded-cavity curves versus thermal lens was calculated and plotted when the astigmation has been taken into account. The problems in the experiments were analyzed and the next improvements were conceived.