Er-yb Co-doped Phosphate Waveguide Laser Characteristics

With the rapid development of optical communication technology,optical waveguide lasers and amplifiers used for high gain, small volume, compact structure, convenient integration and low loss optical communications have drawn more and more attentions. The general development,characteristics and applications of Er³⁺/Yb³⁺ co-doped phosphate glass waveguide laser were summarized. The characteristics of Er³⁺/Yb³⁺ co-doped phosphate glass were introduced. Meanwhile, main methods of fabricating optical waveguide were presented briefly.The characteristics of an Er³⁺/Yb³⁺ co-doped phosphate glass waveguide laser are investigated on the basis of the working theory of a waveguide laser. Using the overlapping factor, the rate-propapation equations of the four-level system of the phosphate glass waveguide laser are simplified. Without taking account of amplified spontaneous emission, the relations between the laser output and the parameters are researched by numerical simulations and the relation curves of Er³⁺/Yb³⁺ ion concentrations, pump powers and waveguide lengths with the laser powers were obtained. The result shows that selecting a right Er³⁺/Yb³⁺ ion concentration is the key for the laser powers were obtained.Traditionally, the numerical analysis for propagation equations of Er³⁺/Yb³⁺ co-doped phosphate glass waveguide laser is obtained by uesing classic Runge-Kutta method. But this algorithm has large amount of calculation and the precision is low. Uesing variable step Runge-Kutta method, the characteristics of phosphate glass waveguide laser is researched for the first time. Every step size can be decided according to local truncation error and the promised precision; additionally, the computing speed can be controlled by adjusting the precision or step size. Simulation results show that variable step Runge-Kutta method can increase the precision and speed compared with classic Runge-Kutta analysis.Based on the data in references, Properties of amplified spontaneous emission(ASE) for the phosphate glass waveguide laser pumped by LD at 980nm have also been studied in detail. Intensity and direction of ASE in the waveguide have been discussed. Considering the structure of energy-level and transition processes of the ions,rate equations and transmitting equations of quasi-three energy-level-system of Er³⁺/Yb³⁺ co-doped phosphate waveguide laser have been presented and analyzed. Threshold of pumping power,slope efficiency and output power have been analysed theoretically.And some other factors which affect the laser have also been discussed.