Research On Optical Parametric Conversion And Dual-Wavelength Q-Switch Based On Periodically Poled Crystal

With the maturity of the fabrication of the periodically poled crystals, the quasi-phase matching (QPM) technique has gained more and more interests in the applications including frequency doubling, different frequency generation, optical parametric oscillation, optical pulse compression, optical filter, optical focus lens, optical deflector, all-optical switch and all-optical wavelength conversion. Now QPM has become a hotspot in nonlinear optics by the virtue of the extremely high conversion efficiency.The main content and key creation points of the dissertation are as follows:1. The QPM intracavity optical parametric generation (IOPG) based on periodically poled crystals internal to an acousto-optically Q-switched Nd:YVO4 laser pumped by a 808-nm diode laser(LD) was demonstrated. Thus a low-pump threshold, compact, high conversion efficiency infrared tunable coherent optical source was obtained.2. The multiple wave conversion based on QPM was investigated and a periodically-phase reversed PPMgO:LN crystal was designed. Optical parametric oscillation(OPO), optical parametric generation(OPG), intracavity optical parametric oscillation(IOPO) and IOPG based on this crystal was demonstrated. For the OPO, with different output coupling mirrors, the dual signal power of 1.9W and dual-idler power of 0.98W was obtained at an incident pump power of 7.6W. For the OPG, the total power of 570mW was achieved, leading to a conversion efficiency of 32.5%. For the IOPO and IOPG, the dual signal power of 0.66W and 0.44W was generated at a 6.1W LD pumping.3. The theoretical model of the axial angle tuned OPO was presented and the experiments based on the PPMgO:LN crystal was demonstrated.4. The theoretical model for generating broadband radiation by using a non-collinear OPG was presented. Using the PPMgO:LN crystal, the bandwidth of 1571~1679nm for the signal wave was achieved.5. A new method for generating broadband radiation by using a non-collinear QPM OPO based on the slant-stripe-type periodically poled crystal is proposed.6. A new approach by use of an electro-optic (EO) aperiodically poled lithium niobate (APLN) is proposed to realize Q-switch operation of the simultaneous dual-wavelength laser (SDWL). Taking the Nd:YVO4 laser at 1.0643μm and 1.3419μm for example, we present the design method of APLN based on simulated annealing algorithm(SA).