The Research Of Rare Earth Doped Phosphate Glass Active Optical Fiber

Erbium doped fiber amplifier(EDFA) is the most important device in the optical fiber communication system,it can amplify optical signals directly without photoelectric conversion.In the traditional EDFA,the concentration of Er³⁺ ions doped in the quartz glass was low,in order to obtain high power output,we have to increase the fiber length generally. This also makes the cost of fiber amplifier system increased and become larger along with the development of photonic integrated technology,the defect is more obvious.This paper in view of the problems above using the solubility of very high phosphate glass as the core materials for the preparation of Yb³⁺+/Er³⁺ co-doped phosphate glass fiber amplifiers.Detailed analysis the energy structure and mixing system related level transition of Yb³⁺-Er³⁺.By analyzing and simplifying the energy level,establishing the equation which could describe the distribution of the mode field in optical fiber and the relationship of the highest gain with the mode field.A series of guiding number will be got after we put the parameters of the optical fiber concrete in the equation.This paper was designed according to the actual needs of phosphate glass substrates,using high temperature melting formula for a series of different Er³⁺/Yb³⁺ ratio formula of Yb³⁺-Er³⁺ co-doped phosphate glasses.After absorption spectroscopy and fluorescence spectroscopy testing we found that by adding Yb³⁺ ions the optical absorption band at 980nm increased largely and with the increase of the Yb³⁺ ions the absorption also increased.When the concentration of Er³⁺ is 2.35×10²⁰ions·cm³⁺,the mixing ratio of Yb³⁺/Er³⁺ is 1:8,the fluorescence intensity of phosphate glass is the best.According to testing results of the absorption and fluorescence spectroscopy,with theoretical calculation Calculate theΩ₂,Ω₄,Ω₆ in the different ratio of the Er³⁺/Yb³⁺ in phosphate glass and the ⁴â… _13/2â†'⁴â… _15/2 transition probability radiation and fluorescence life by using J-O Theory and analyzed the component changes with the effect ofΩ₂,Ω₄,Ω₆.According to the preparation of Yb³⁺/Er³⁺ the various parameters of mixed phosphate glasses,designed a kind of optical fiber which the core diameter is 6um,the inner layer is 62.5um,outsourcing layer is 125um,numerical aperture(NA)of the core is 0.16,numerical aperture(NA) of the cladding is 0.45 in double cladding Er³⁺/Yb³⁺mixed phosphate glass fiber.Using the fiber amplifier software OptiSystem.The 5cm long Er³⁺/Yb³⁺ co-doped double-clad fiber were simulated and analyzed,in 1.534 um wavelengths can got the gain of 3.51dB/cm.The double-clad fiber amplifier has good performance of amplification to the small signal.