Investigation On Preparation And Characteristics Of Waveguides In Erbium-Doped Germanate Glass

The performance of optical waveguides,which process information in the micron scale,plays a key role in the quality of integrated optical systems.At present,various techniques for preparing optical waveguide structures have become increasingly mature.Among which ion implantation,as a method for preparing one-dimensional optical waveguide,has strong applicability to the substrate materials and does not change the inherent properties of the substrate materials.The implantation conditions can be controlled,and further annealing operation can recover the damage caused by ion implantation to the materials to the greatest extent.Ion implantation technology can be combined with diamond blade dicing to produce two-dimensional optical waveguide structures.Two-dimensional optical waveguides can constrain light propagation in both directions,which transmits light with a higher density and is easier to integrate.The erbium-doped germanate glass is a kind of glass with high solubility of rare earth ions and low energy of phonons,which can effectively reduce the probability of polyphonon emission,and doped Er³⁺ions can obtain high efficiency transition emission in it.Therefore,the erbium-doped germanate glass waveguides can be used as amplifying substrates for waveguide amplifiers and waveguide lasers.It has a good application prospect in the field of communication transmission and optical materials.In this paper,the erbium-doped germanate glass is used as substrate material,and the ridge waveguide structure adopts the method of ion implantation combined with precision diamond blade dicing.Among them,the ion implantation uses light ions（H⁺ion,He⁺ion）,and the optical properties of the ridged waveguides after two different light ion implantation and cutting are tested respectively.It provides the experimental basis for the fabrication of waveguide laser with the erbium-doped germanate waveguide as the core.The main contents and achievements of this paper are as follows:1.Study the spectral properties of erbium-doped germanate glass and its Judd-Ofelt theoretical analysis.The refractive index,transmittance,absorption spectrum,fluorescence spectrum and fluorescence lifetime of the erbium-doped germanate glass were measured.The erbium ions of strength parameters is calculated by using the theory of Judd-Ofelt in glass areΩ₂=5.2047?10^-20cm²,Ω₄=2.6223?10^-20 cm²,Ω₆=1.6491?10^-20 cm²,and also calculated the test and theory oscillator strength,the spontaneous transition probability of erbium ions,fluorescence branching ratio and fluorescence radiation lifetime.According the absorption and fluorescence spectrum calculate the absorption cross section(8.1272×10^-20 cm²),launch section(9.5439×10^-20 cm²),gain cross section and the erbium ions level ⁴I_13/2→⁴I_15/2 emission fluorescence half width is 110nm,the maximum gain coefficient of Er³⁺ions at 1528 nm is 3.04 cm^-1.The experimental data show that the erbium-doped germanate glass has good laser gain performance and can be used in laser or amplifier to achieve broadband and high gain amplification.2.Fabrication and optical properties of erbium-doped germanate glass ridge waveguide by hydrogen ion implantation combined with precision diamond blade dicing.Planar optical waveguide structures were formed near the surface of the polished erbium-doped germanate glass samples by H⁺ion implantation.The sample size is 10×5×1 mm³.The H⁺ions implantation conditions are energy of 400 ke V and dose of 8.0×10¹⁶ ions/cm².The simulation data of SRIM software show that the range of H⁺ions that after entering the erbium-doped germanate glass is about 3.81μm,which is roughly consistent with the thickness of waveguide layer measured under the optical microscope.According to the dark model property curve,the erbium-doped germanate glass planar optical waveguide formed by H⁺ion implantation has three guide modes that the refractive indices are lower than the substrate refractive index,indicating that the refractive index of sample waveguide region decreases due to H⁺ion implantation.The refractive index distribution fitted with RCM proves that the optical barrier waveguide structure is formed by H⁺ion implantation of the erbium-doped germanate glass.The near-field light intensity distribution obtained by the end-coupled system shows that the light is well confined in the waveguide layer,the light intensity distribution is relatively continuous and no obvious light leakage occurs,which indicates that the prepared erbium-doped germanate glass planar waveguide has good light conduction characteristics.On the basis of the planar optical waveguide,the use of precision diamond blade dicing cut six ridge optical waveguide structure,width of 45μm×2,35μm×2,25μm×2,based on the end coupling system,the ridge waveguides modes are measured,results show that the ridge waveguide has the transmission limit function in horizontal and vertical direction.3.Fabrication and characterization of the erbium-doped glass ridged waveguide structures by helium ion implantation combined with precision diamond blade dicing.Under the condition of vacuum,the energy of 400 ke V after ion accelerator acceleration,the dose of 6.0×10¹⁶ ions/cm² helium ion beam implantion to the size of 10×5×1 mm³ erbium doped germanate glass samples of glass surface to form a depth of 1.8μm planar optical waveguide structures.Then,a precision diamond blade with a speed of 0.1 mm/s and a rotation speed of 20,000rpm was used to cut the different widths ridge structure on the surface of the planar waveguide.The formation mechanism,refractive index distribution and field intensity distribution of planar waveguides are investigated by SRIM,RCM and finite-difference beam propagation method（FD-BPM）.The dark model curves show that the planar waveguide has two guide modes,and the refractive index distribution is“optical barrier+optical enhanced well”.The end face coupling experiments proves that both planar and ridge waveguides have good light-guiding properties.The basic structure of the erbium-doped germanate glass waveguide laser is designed,and an experimental platform of laser pumping is built according to the design scheme.