Study On Properties Of Yttrium Gallium Garnet And Silicon Carbide Crystals By Ion Irradiation

As the basic structure of integrated optics,optical waveguides can be used to connect various optical components integrated on a substrate and are the basis for various integrated optical devices.Since the performance of optical waveguides directly affects the quality of the entire integrated optical system,the preparation of high-quality optical waveguides with superior performance has been one of the aims of integrated optics field.Ion irradiation or ion implantation as an effective way of material surface modification,can be used to prepare optical waveguide,and is widely used in metals,semiconductors,optical crystals,ceramics,polymers and other materials.The ion implantation process can be simulated by SRIM(the Stopping and Range of Ions in Matter)software,and the ion range,electronic energy loss and nuclear energy loss can be calculated.After ion implantation,partial lattice damage can be recovered and the implanted ions can be activated by annealing process.The refractive index distribution,near-field light intensity distribution,and losses of optical waveguides can be measured by prism coupling method and end-face coupling methods.The effect of the ion irradiation process on the fluorescence properties and lattice structure of the crystals can be tested by micro-fluorescence spectroscopy,Raman spectroscopy,and Rutherford Backscattering/channeling spectroscopy.The surface appearance of the crystals before and after ion irradiation can be characterized by atomic force microscopy and transmission electron microscopy.The work in this paper mainly involved with ion irradiation or ion implantation on yttrium gallium garnet and silicon carbide and consists of three main components:preparation optical waveguides by swift heavy ion irradiation on neodymium-doped yttrium gallium garnet(Nd:YGG)crystals;preparation optical waveguides by multi-energy He ion implantation on ytterbium-doped yttrium gallium garnet(Yb:YGG)crystals;and damage studies in multiple fluences of P ion irradiation on 4H silicon carbide(4H-SiC)crystalsA high quality refractive index-enhanced well type planar optical waveguide was fabricated by 30 MeV swift Kr8+ irradiated into the Nd:YGG crystal at a fluence of 2×1012ions/cm2.This waveguide can effectively avoid the tunneling effect;its transmission loss is low to 0.8dB/cm measured by the end-face coupling method.Because of the ultra-low irradiation fluence,the displacement per atom(dpa)of this waveguide is also very low(0.0012),which is conducive to ensure the surface quality of the material.There is a greater application potential in the high crystal quality requirements application devices.After ion irradiation,the fluorescence emission characteristics and Raman characteristics of Nd:YGG crystal are well preserved.Based on these analyses,we have explored suitable waveguide preparation conditions through a large number of experimental studies,provided a competitive Nd:YGG crystal waveguide preparation method and an experimental basis for the application of the crystal in the field of integrated opticsMultiple-energy(400keV+450keV+500keV)He ions were implanted into Yb:YGG crystals at a total fluence of 9.6×1016 ions/cm2 and the thickness of the waveguide is about 1?m.The sequence annealing treatment results show that the planar waveguide could sustain thermal stability when the annealing temperature is less than or equal to 500? on the one hand,and that surface blistering is induced after more than 500? annealing process on the other hand.This work combined with the Bonding technology has reference value in the preparation of Yb:YGG thin filmDifferent fluences of 100 keV of P ions were irradiated into 4H-SiC crystals at room temperature,and lattice damage of 4H-SiC after ion irradiation was measured by Rutherford backscattering and transmission electron microscopy.According to the results of Rutherford backscattering,transmission electron microscopy and SRIM simulation,we consider the amorphous damage threshold of P irradiated 4H-SiC crystals to be about 0.3 dpa.The expansion of the 4H-SiC surface after irradiating with 100 keV,1.0×1015ions/cm2 was found to be about 10%.From the results of prism coupling,lattice damage can be partially recovered after annealing.We can conclude that the lattice quality is deteriorated and more optical absorption centers were induced with increased of P ion fluence in the surface of 4H-SiC crystal according to the Raman and absorption spectroscopic measurement.This work provides reference data for selective doping of silicon-based electronic devices.