Study On Preparation Of Nd:YAG Crystal Core/Glass-Clad Composite Optical Fiber

Stimulated Brillouin scattering?SBS?limits the increase of the limit output power of single glass fiber.The yttrium aluminum garnet?YAG?crystal has an SBS gain coefficient that is one order of magnitude lower than that of glass.YAG crystal fiber combines the advantages of crystal and fiber,which can effectively reduce non-linear effects and thermal damage while achieving higher power output.Therefore,this article uses rare-earth-doped YAG crystal cores and high-refractive-index glass cladding to prepare composite optical fibers.The purpose is to study the preparation process and properties of rare-earth-doped YAG crystal core/glass-clad composite optical fibers.And study the temperature-variation spectrum and radiation resistance of Nd³⁺doped phosphate glass,silicate glass,silica glass,YAG single crystal and YAG ceramics,It is hoped to obtain a breakthrough in the preparation process of rare-earth-doped YAG crystal core/glass cladding composite optical fiber,realize laser output,and provide reference and basis for subsequent research through temperature-variant spectral analysis and radiation resistance experiments.The details are as follows:The effects of heating tools,containers,and temperature of the hot phosphoric acid etching method on the preparation of small-diameter Nd:YAG crystal cores were studied.It was found that heating to 250oC using corundum crucibles and muffle furnaces can effectively reduce the Nd:YAG crystal core Diameter to obtain a fine Nd:YAG crystal core with a diameter of about 100?m;Using high-temperature melting method to prepare cladding glass,the influence of La₂O₃,Nb₂O₅,Pb O and other components on refractive index,thermal expansion and crystallization ability were studied.It was found that increasing the content of La₂O₃,Nb₂O₅,Pb O can increase the refractive index and thermal expansion,and the glass is easier to crystallize,of which borate glass with a refractive index of 1.805and a thermal expansion coefficient of 6.75×10-6/oC is crystallized after holding at 800oC for 15minutes,while the refractive index is 1.803 and the thermal expansion coefficient is 6.66×10-6/oC The germanate glass was crystallized after holding at 700oC for 30 minutes.Using fiber drawing tower to prepare N3122 phosphate glass capillary,It was found that N3122phosphate glass capillaries of different sizes with inner diameters of 200-300?m can be drawn under the conditions of material dropping temperature of 555oC and drawing temperature of 521oC;The Nd:YAG crystal core/glass-clad composite optical fiber was prepared by the low-temperature collapse method,and a composite optical fiber with a length of 10 mm and a core diameter of 100?m was obtained;microscopic observation revealed that the composite optical fiber still maintained a relatively complete structure,and Raman spectroscopy test proved There is no component diffusion between the core and the cladding,which solves the problem of core amorphization.Combined with Judd-Ofelt theoretical analysis,the temperature resistance and radiation resistance of Nd³⁺doped phosphate glass?N3122,N3135?,silicate glass,silica glass,Nd:YAG single crystal and Nd:YAG transparent ceramic were studied.It was found that increasing the temperature and irradiation will increase the fluorescence branching ratio and effective line width,reduce the quantum efficiency,absorption cross-section and emission cross-section,and the emission cross-section changes approximately linear;The temperature rises from 30oC to 120oC,the emission cross-sections(×10^-20 cm²)of N3122,N3135,silicate glass,silica glass,Nd:YAG single crystal and Nd:YAG transparent ceramic were reduced from 3.27,3.68,1.66,0.86,8.39,5.96 to 2.81 3.14,1.31,0.75,8.04,5.60;Irradiated at 0.3388 Gy/min radiation dose rate for 17 hours,The emission cross-sections(×10^-20 cm²)of N3122,N3135,silicate glass,silica glass,Nd:YAG single crystal and Nd:YAG transparent ceramic were reduced from 3.76,3.72,1.70,0.91,8.97,5.99 to 3.24,3.42,1.65,0.87,8.66,5.95.