Research On High-powered Er-Yb Co-doped Double Cladding Fiber Amplifier

Optical fiber amplifiers are promising devices to be used in realizing the direct in-line amplification of optical signals in optical fiber communication systems. EDFA (Erbium-Doped Fiber Amplifiers) owns the properties of lower noise,high gain,wide bandwidth,high pump efficiency and stable work performance.It's used widely in the long-haul optical communication systems, especially in WDM (Wavelength Division Multiplexing) optical fiber communication systems. However,with the increase of the transmission channels and the enhancement of the transmission bit rate and the increase of the transmission distance in the WDM optical fiber communication systems, constant gain over a wide spectral range in EDFAs is required for WDM applications. In order to get high power operation, it is necessary to use high erbium concentration and a double-clad fiber. However the ion-ion interactions which causes pair-induced up-conversion depletes the erbium metastable level and lowers the efficiency for concentration above a few hundred parts per million (ppm) of Er. A means of addressing this issue is by co-doping the Er doped fiber with Yb. The presence of Yb reduces the formation of Er clusters and reduces the up-conversion rate from significantly. This allows high erbium doping level needed for a high gain amplifier. In addition, an energy transfer from Yb to Er provides an efficient indirect pumping mechanism of Er ions. This energy transfer mechanism is very efficient. We can achieve higher output signal power with very short Er-Yb co-doped double cladding fiber especially using the embedded mirror side pumping method.In the first chapter of this paper the development history of the fiber optical amplifier has been reviewed and the types ,the development directions ,the new progress of the fiber optical amplifiers have been introduced.In the second chapter the structure of the double cladding fiber and optimization of the fiber's inner cladding has been introduced.Then the calculation of the fiber's parameters and the materials of the fiber has been mentioned . The third chapter is mainly about the coupling methods and it's theory analysis.In the last chapter we talks about the structure of the amplifier and how to choose the equipments used in the amplifier.The rate equations and dynamic transition equations have been studied after the system's energy transitions level anaysis .The research of Er 3 + Yb3+co-doped fiber amplifier is carrying in experiment. The Er 3 + Yb3+co-doped double cladding fiber is produced by Nufern, the pumping resource wavelength is 975nm, the maximum pumping power is 4W. The output signal wavelength is 1535nm, and the maximum output power is about 1.7W.