Fabracation Of Two-dimensional Waveguides On Magneto-optical Crystals And Characterization For Magneto-optical Properties

As the channel of micron-level information processing,optical waveguide is the bridge of information transmission after the integration of micro-devices.The performance of the optical waveguide is the key factor in determining the quality of the integrated optical system.Optical waveguide isolator is a micro magneto-optical device based on the waveguide structure,which only allows optical signal to propagate in one direction.Hence,the fabrication of waveguide structures with low propagation loss and excellent optical properties is of great significance for promoting their applications in optical waveguide isolators.In this paper,magneto-optical rotation crystals TGG and TSAG are used as substrate materials,and two-dimensional optical waveguide structures with different widths were fabricated by means of ion implantation combined with precise diamond blade dicing.The optical properties of TGG and TSAG crystals and their waveguides were investigated,and the rotation angles of the substrate material and the two-dimensional optical waveguide region under a constant magnetic field were measured.The work in this paper provides experimental and theoretical basis for the fabrication of two-dimensional waveguide structures on TGG and TSAG crystals,and opens up a new method for the fabrication of waveguide isolators based on magneto-optical crystal waveguides.The main work and achievements of this paper are as follows:1.Fabrication for two-dimensional optical waveguide structure of TGG crystal by helium ion implantation combined with precision diamond blade dicing and study on its magneto-optical properties.Helium ions with an energy of 400 ke V and a dose of 6.0×10¹⁶ions/cm² were implanted into a TGG crystal sample with a size of 10×5×2 mm³ to form a planar optical waveguide structure.The experimental results show that the helium-ion implanted TGG planar optical waveguide has two guiding modes,and the refractive index of the guiding mode is lower than that of the substrate.It is proved that the refractive index of the waveguide region decreases due to helium ion implantation,and the experimental results depict that the waveguide region has good light-guiding characteristics.Based on the TGG planar waveguide,the two-dimensional optical waveguides with widths of 30μm and 45μm were fabricated by dicing several air grooves with the precise diamond blade.The confinement effect on light propagation of two-dimensional optical waveguide in the horizontal and vertical directions was studied.The rotation angle of the TGG two-dimensional optical waveguide with the width of 30μm was 8°under the condition of 155 m T constant magnetic field.2.Fabrication for two-dimensional optical waveguide structure of TSAG crystal by helium ion implantation combined with precision diamond blade dicing and study on its magneto-optical properties.An optical planar waveguide structure with a depth of 1.05μm was formed by implanting helium ions with an energy of 400 ke V and a dose of 6.0×10¹⁶ ions/cm² into the surface of TSAG crystal sample with a dimension of 10×5×2 mm³.The experimental results show that the TSAG planar waveguide has two guided modes whose refractive index is lower than that of the substrate.The TSAG planar waveguide was manufactured by precise diamond blade to form two-dimensional optical waveguides with widths of 30μm and 45μm,respectively.The near-field intensity distribution of the 45μm TSAG two-dimensional optical waveguide presents multiple modes.The optical rotation angle of the 30μm TSAG ridge waveguide is measured to be 13°at a constant magnetic field intensity of 155 mT.