Study On Active Mode-locking Intra-cavity Doubling Nd:YAG Green Light Laser

The continuous Nd:YAG green light laser and the mode-locking Nd:YAG green light laser are commomly used in the field of the produce , research , communication, medical treatment, military affairs and entertainment. This dissertation systematic presented the theory of the Nd: YAG green light laser, which included the characteristic of Nd: YAG crystal; the principle of optical pump system and thermal effects; thermal stability of optical resonator; the quasi-classical theory of second harmonic generation(SHG) ; the theory of intra-cavity double frequency ; the characteristic of the biaxial nonlinear crystal KTP; the principle of active mode- locking laser ; the theory of the SHG of mode-locking pulse.In this dissertation, we developed an active mode-locking intra-cavity doubling Nd:YAG green light laser pumped by the continuous krypton lamp. By the means of all condenser cavity water cooling.we efficiently reduced the worsening of the quality of laser which came from the thermal effects of lamp pump system. On the basis of analysis of thermal stability resonator , we worked out the stable area of the plano-plano cavity which helped deciding the optimum positions of the laser crystal and the doubling crystal. In the experiment of mode-locking laser SHG , we considered that the mode-locking and the SHG restricted each other and indicated that the group velocity mismatch(GVM) from the spectrum widening of mode-locking pulse was the main reason which took responsibility for the restraint of SHG conversion efficiency. We finally achieve the 4.8W output power of continuous green light at 2200W input electrical power, whose electrical-to-optical conversion efficiency was about 0.2%, and 6W output power of mode-locking green light at the same maximum input power.This dissertation also discussed the probability of raising SHG the conversion efficiency: using two-pass SHG instead of one-pass SHG by adding reflecting mirror to cavity; realizing polarized matching by adding polaroid sheet to cavity; using instable resonator to lower phase mismatch.