Study On Resonator And Coupling System Of Laser Diode End-pumped Nd:YVO₄Solid-State Lasers

The laser diode pumped second generation solid state lasers have obvious advantages inaspects of energy conversion efficiency, stability, service life, volume and beam quality.Besides, they have already been widely used in communication, medical treatment, scientificresearch and material processing, and their market is still promising. In order to decrease thebeam divergence angle, based on the four-level theory of lasers, research of end-pumpedsolid state lasers about resonator and coupling system designing were carried out.The main contents of this article were summarized as follows:(1) In this dissertation, characteristics and application of end-pumping and side-pumpingmethod were compared. Several coupling system of the diode pumped solid state lasers weresummarized and compared. Finally, the application fields and research significance of diodepumped solid state lasers were introduced.(2) Based on the four-level theory of the lasers, the influence of pumping-spot size andoscillation spot size, crystal length, coupling transmittance to the output characteristics ofdiode end-pumped solid state lasers were deeply studied. The thermal lens effect of lasercrystal was simply researched. Finally, some output characteristics of diode end pumpedlaser and thermal lens focal length of the laser crystal were numerically simulated.(3) A kind of collimating focusing coupling system was designed. The coupling systemwas made of plano-convex lens, the shape of the pumping spot was regular, and the couplingefficiency reached to approximately91.5%in the experiment test result, and this result metthe design goal.(4) The theory of the resonator cavity was deeply researched, and we designed a kind ofplane-concave resonator which had big curvature radius and long cavity length. And it hadgood stability in the experiment. We got a3.502W continuous output power at the pumpingpower of12.01W. The optical-to-optical efficiency and slope efficiency were30%and50%respectively, and finally the beam divergence angle of about2.2mrad was achieved.