Preparation Of Terbium Gallium Garnet Crystal Material For Optical Fiber Communication

The quality of magneto-optical materials directly determines the performance of optical isolators,and plays an important role in the field of optical communication and integrated optics.Terbium gallium garnet(Tb₃Ga₅O₁₂,terbium gallium garnet,TGG)is a kind of high-quality magneto-optical material,which has good non heterogeneity and wide application range.It can be used in optical fiber isolator,optical fiber current sensor,laser gyro and magneto-optical display.Based on the appeal,this thesis analyzes the growth equipment,raw material preparation,polycrystalline material synthesis,temperature field design,process design and other aspects of the terbium gallium garnet material,completes the processing and testing of the crystal material,and prepares the terbium gallium garnet crystal material which can meet the needs of high-performance optical isolators.The main contents are:In this thesis,we study and discuss the problem of appeal in the aspects of growth equipment,raw material preparation,polycrystalline raw material synthesis,temperature field design,process design and so on,and test the final growth of crystal materials.Terbium gallium garnet crystal material which can meet the needs of high performance optical isolator was prepared.The main contents are:1.The synthesis technology of terbium gallium garnet polycrystalline material was studied.The synthesis method of TGG polycrystalline material was compared,and the solid-phase synthesis method was selected.The raw materials of terbium oxide and gallium oxide are analyzed and tested,and the raw material ratio and process environment for TGG polycrystalline raw materials are preliminarily calculated.By optimizing the ratio of raw materials and polycrystalline synthesis process,the polycrystalline raw materials with single crystal phase are prepared,so as to reduce the defects caused by bubbles and impurities in the process of crystal growth.2.The growth technology of terbium gallium garnet was studied.The crystal growth mode was studied.TGG crystal was grown by Czochralski method.TGG in the direction of{111}is used as the crystal seed to design the temperature field.The narrow inverted"V"type small hole observation window and transparent quartz glass block are used to design the observation window in the crystal growth process,which can successfully observe the crystal growth and avoid the temperature field fluctuation caused by the change of the external environment.Through theoretical research,preliminary design of process parameters needed for crystal growth,and then through the practical problems encountered in many experiments,such as spiral,cracking,cloud layer,etc.,analysis and comparison were carried out and process modification was carried out,which laid the foundation for the growth of high-quality large-size TGG.3.The grown crystals are processed by orientation,slicing,polishing,etc.,and tested by magneto-optical and optical properties.For the items lacking test conditions,they are sent to other testing institutions for tripartite test,and finally the properties are characterized.The crystal size is up toФ53×80mm,and the feld constant is 39.9 rad/T·m at 1064nm,the transmittance is more than 80%,and the thermal conductivity is4.482 w/m·K.