Melting And Characterization Of Er³⁺ And Yb³⁺ Doped Phosphate Glass For Waveguide Fabrication

During the past several decades,as the most fundamental and indispensible component,optical waveguide gets more and more attention.Optical devices based on glasses have many advantages over other technologies,for example low intrinsic absorption in the near infrared region of the spectrum,minimized coupling losses to optical fibers,and no intrinsic material birefringence compared to crystalline semiconductors,etc.Phosphate glasses are regarded as excellent glass host for waveguide laser fabrication mainly because it has high solubility of rare earth ions compared with other oxide glasses,which allows for high doping concentrations without significant lifetime reduction,and this will bring high signal gain.Ion exchange has been widely used in fabricating low-loss glass waveguide since it has various superiority over other fabrication techniques like chemical vapor deposition and optical writing,such as high reliability,massive production,easy fabrication of single-mode waveguide,excellent mode matching to single-mode fiber through waveguide burial and low birefringence across a broad range of waveguide widths.Er³⁺/Yb³⁺ codoped alkaline aluminum phosphate glasses have been designed and fabricated,and a series test has been done in this work.Main achievements are listed as follows:1.Er³⁺/Yb³⁺ codoped alkaline aluminum phosphate glasses have been designed and fabricated based on the molar composition 67 NaPO₃: 4Mg?PO₃?₂: 4Al₂O₃: 25Al?PO₃?₃,which can be called NMAP glass for short.Additionally,2.0wt% Er₂O₃ ? 4.0wt% Yb₂O₃ has been added into the composition.The density of glass sample is measured by Archimedes Method,and the refractive index by Metricon 2010 prism coupler.DTA curve of the glass sample is obtained by WCR-2D differential thermal analyzer,transition temperature is obtained and the thermology performance is characterised.2.Ion exchange process has been achieved,which is submerging the glass sample into the KNO₃ fused salt under 390? for 2h.The effective diffusion coefficient De is deduced to be 0.11 m m2/min,indicating that ion exchange process has been achieved thoroughly in the optical glass.The optical performance of the Er³⁺/Yb³⁺ codoped NMAP glass has been obtained.The refractive index of the glass sample is measured by Metricon 2010 prism coupler,and the refractive index of the slab waveguide surface n0 and the substrate nsub are1.5262 and 1.5182 at 632.8 nm,respectively.The absorption spectrum and emission spectrum has also been measured.3.Judd-Oflet calculation has been done in this work.The J-O intensity parameters ?_t?t=2,4,6?are 5.47?10^-20,1.34?10^-20,0.81?10^-20cm² respectively,and the root-mean-square deviation drmsis 2.79?10^-7,indicating that the calculation is reliable.These data shows that Er³⁺ is in a strong asymmetrical and covalent environment in the optical glass,and ?4/ ?6 is calculated to be 1.65,indicating the glass sample has an excellent spectroscopic quality.4.The spontaneous transition parameters of Er³⁺,mainly including the spontaneous transition probability A,fluorescence branching ratio b,emission lifetime trad.The signal gain of the Er³⁺/Yb³⁺ codoped NMAP glass sample.The gain spectrum G??,p? can be calculated by the following formula: G??,p?=10log₁₀exp{N[p?_e???-?1-p??_a???]L}.When the ratio of the Er³⁺ in ⁴I_13/2 energy level reaches 0.8 and 1.0,the calculated net gain are 2.97 dB/cm ?4.77 d B/cm,respectively.