| Mid infrared 8~10μm laser is widely applied in such fields as electro optical countermeasures, environmental monitoring, laser radar, laser medical treatment, and spectroscopy studies. The 2μm laser pump ZGP optical parametric oscillator is an effective means of obtaining the 8~10μm laser. Moreover, the 2μm laser is also at the position of the atmospheric window; therefore, it is a perfect light source in these areas like laser ranging, laser radar, laser remote sensing, laser imaging, and laser surgery. As for the 2μm laser, LD pump Tm, Ho laser is an effective way of getting it. Above all, this paper has very significant contents, with its main focus on obtaining of the high power 2μm laser, which is based on the combined study of the theories and practices of the LD pump Tm,Ho laser, ZGP OPO, and related techniques.As for the theory, this paper mainly analyses the Tm,Ho laser theory, and the OPO theory. As for the Tm,Ho laser theory, this paper , on the basis of the energy level structure, analyses the crystal Tm,Ho:YAP & Tm,Ho:GdVO4 absorption spectrum at 800nm, and the emission band spectrum at 2μm. As far as the above transitions concerned, this paper builds up standard four-level rate equation, and analyses the pumping threshold and slope efficiency of the Tm,Ho laser. From the motion equations of the laser field, this paper analyses the photon gain and photon loss of the cavity resonator, and the influences on photon gain and photon loss given by mode volume. In respect of the OPO theory, based on the steady coupled wave equations, this paper analyses the OPO light gain, photo threshold, and the laser conversion efficiency; then compares the SRO and DRO photo threshold and efficiency; and finally comes to the conclusion that the phase matching is the OPO best functional mode. Moreover, according to the phase matching, this paper analyses the OPO output wavelength tuning techniques, and gets the specific output wavelength, and the crystal's best cutting angle. Also, on the basis of the introduction of the ZGP crystal's materializing and optical characters, as well as the calculated curved paths of the phased matching, tuned with the incidence angle, when different pumps ZGP OPO I&II are used, this paper analyses the wavelength tuning characteristics of the Tm,Ho:GdVO4 laser pump ZGP OPO. In respect of the experiments, first, this paper comparatively studies the Tm,Ho:YAP & Tm,Ho:GdVO4 crystals, designs Tm,Ho laser, and gets 8~10μm laser output from its pump ZGP OPO. Second, this paper studies cavity resonator parameter influences on Tm,Ho:YAP & Tm,Ho:GdVO4 laser laser output power, delivery efficiency, cavity resonator stability as well. Third, based on the experiments, this paper designs Tm,Ho:YAP & Tm,Ho:GdVO4 laser, of the LD twin-end pumps, with liquid nitrogen refrigeration and high beam quality, among which, c-cut Tm,Ho:YAP laser, for the first time, realize 2044nm & 2132nm dual wavelength continuous and pulsed laser output. At 2044nm, the continuous output power is 9.30W, light- light conversion efficiency is 37% and slope efficiency is 41%, while at 2132nm, the continuous output power is 8.76W, light- light conversion efficiency is 35% and slope efficiency is 42%. In cold operation, the b-cut Tm,Ho:YAP obtains 2120nm laser output, continuous output power 8.36W, light-light conversion efficiency 33%, and slope efficiency 42%, which optimizes the 2μm laser wavelength, pump facula size and monopulse energy, and which reduces 8~10μm ZGP OPO threshold. Finally, through the study of relationship between the 8~10μm ZGP OPO output wavelength and pump laser incidence angle, the paper discovers that, at 8~10μm, the top performance wavelength is 8.08μm, with corresponding crystal cutting angle 51.4°. When ZGP OPO is in motion at 8.08μm, this paper studies the output power correlation parameter and transfer efficiency correlation parameter, which influence ZGP OPO, and also obtains the best pump facula 0.85mm, the best cavity resonator length 32 mm, the best crystal temperature 15oC~19oC, and the highest output power 1.44W.
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