| Laser technique has played an important role in many areas, such as industries, agriculture, communications, medicine and national defense etc. Presently, to explore multi-functional crystal materials, which possess both laser and nonlinear optical performances with the capabilities of expanding the range of laser wavelengths and designing miniature, portable and stable devices, is the main trend of the laser development.In order to explore and enrich more multi-functional crystal materials with laser frequency doubling function, many experiments of growth on the A3TaGa3Si2O14(ATGS,A=Ca,Sr) crystal and Nd3+ doped ATGS(A=Ca,Sr) single crystal were done, nonlinear optical performance and laser self-frenquency-doubling performance were studied in this paper. And the main contents of this thesis are followed:(1) The Ca3TaGa3Si2O14(CTGS) and Sr3TaGa3Si2O14(STGS) and the doping concentration 1mol% Nd2O3 of ATGS(A=Ca,Sr) single crystals were grown by Czochralski method. The optimal growth directions of crystal growth were studied and it is found that the CTGS and STGS single crystal can show high quality along [110] and [120] direction, respectively. The defects of growth crystal were discussed (including crystal crack, inclusions and color center etc.), researches show the defects can avoid and reduce effectively by adjusting the temperature field, regulating growth parameter and annealing treatment.(2) The structure characterizations and optical properties of ATGS(A=Ca,Sr) and Nd:ATGS(A=Ca,Sr) single crystals were described. The X-Ray diffraction analyses confirm that all grown crystals were single phase, and both belong to trigonal system and 32 point group. The top and bottom of Nd3+doped CTGS and STGS crystal were studied by the the X-Ray diffraction, and the resules were:the crystallineinterplanar spacing was slightly larger after doping Nd3+, and the botton changed more obviously.Crystal quality of Nd:CTGS crystal was characterized by using High Resolution X-Ray Diffraction technique. The X-Ray rocking curve peak shape symmetry of the center and fringe of Nd:CTGS crystal, and has low full width at half-maximum values, which indicate the high quality of grown crystal.The Nd3+ doping concentration in Nd:CTGS and Nd:STGS crystals were measured by X-Ray fluorescence spectrometer. The measured results indicate that the doping concentration of Nd3+ were 10.7520% and 6.4516% in Nd:CTGS and Nd:STGS crystals respectively, and the segregation coefficient were 0.420 and 0.311, respectively.The transmission spectrums of ATGS(A=Ca,Sr) and Nd:ATGS(A=Ca,Sr) crystals were measured. The results show that the transmittance of the grown crystals was almost above 80%, indicating the good optical homogeneity.The fluorescence spectrum for the Nd:CTGS and Nd:STGS crystal were recorded at ambient temperature. There were three flurescence bands which centered near 893nm,1064nm and 1344nm in Nd:CTGSand Nd:STGS crystal and the peak near 1064nm was strongest.The refractive indices of CTGS and STGS crystals were measured by vertical-indidence method. The refractive indices were fitted with the Sellmieier equation and then the Sellmeir parameters were obtained. The measured results show the four crystals are all positive uniaxial crystals.(3) According to the refractive indices of CTGS and STGS crystal, the phase matching (PM) angles were got which based on the theoretical calculation and experiment. They were:for CTGS crystal:type 1(38.7°,30.0°) and type 11(61.1°,0°); STGS crystal:type Ⅰ(42.5°,30.0°) and type Ⅱ(69.5°,0°), respectively. The CTGS and STGS crystal samples were prepared along the PM directions. For CTGS crystal, the largest green laser light output we got were:5.30 mW(type Ⅰ) and 4.02 mW(type Ⅱ), and the the power conversion efficiency were 20.38%(type Ⅰ) and 16.33%(type Ⅱ), respectively. The effective second-order nonlinear coefficient were deff(type Ⅰ)=0.44pmV-1 and deff(type Ⅱ)=0.34pmV-1, second order nonlinear optical parametersx11 were 0.73pmV-1.The SHG experiment with STGS crystal was made under the same experimental conditions. The largest green laser light output we got were:3.16mW(type Ⅰ) and 2.17mW(type Ⅱ), and the the power conversion efficiency were 12.89%(type Ⅰ) and 10.71%(type Ⅱ), respectively. The effective second-order nonlinear coefficient were deff(type Ⅰ)=0.39pmV-1 and deff(type Ⅱ)=0.24pmV-1, second order nonlinear optical parametersx11 were 0.72pmV-1.(4) The self-frequency doubling (SFD)experiments were realized in Nd:CTGS and Nd:STGS crystal. The largest output values were 18.8mW for type Ⅰ crystal cut and 4.4mW for type Ⅱcrystal cut in Nd:CTGS crystal, respectively; The largest output values were 9.0mW for type Ⅰ crystal cut and 2.0mW for type Ⅱcrystal cut in Nd:STGS crystal, respectively.The Nd:CTGS crystal which using coated system in different wavelengths for anti-reflection and high-reflection was used for SFD to obtain larger green laser light. The maximum power was 72 mW in the type I crystal cut and 33.68mW in the type II crystal cut. Therefore, the stability of the output power in 30mins was measured, the power was very smooth and nearly without fluctuation. |
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