Study On Application Of Single Channel EDFA To Metropolitan Area Network

Optical fiber amplifiers are promising devices to be used to amplify the optical signals in optical fiber communication systems. EDFA (Erbium-Doped Fiber Amplifier) owns the properties of low noise, high gain, wide bandwidth, high pump efficiency and high stability. It's widely used in the long-haul optical communication systems, especially in WDM (Wavelength Division Multiplexing) optical fiber communication systems.However, it is not very popular to use an Multi-channel EDFA in the Metropolitan Networking, because of its high cost. Since a filter is usually put into an EDFA module to flatten the gain spectrum, resulting in the high cost. Moreover the gain flatness of multi-channel EDFA may not be guaranteed in some conditions, this lead to the small dynamic range of gain and less flexibility in the Metropolitan Are Networking.Although the spectrum of Single-channel EDFA is not flat, it is attractive to find its application to the WDM MAN because of its low cost and flexibility. We can use a single-channel EDFA in WDM MAN by optimizing its parameters so that the cost can be lowered.The theoretical model of EDFA is introduced based on rate equations and transmission equations, and the gain, saturation output power and noise figure are studied in detail. Based on the theoretical study, a Single-channel EDFA is designed for WDM Metropolitan networks applications as pre-amplifier, not only lowering the cost but also sustaining the flexibility of the system. The dynamic properties of EDFA are also studied. Several Gain-clamped methods have been demonstrated to control the dynamic gain variation. In order to study the properties of EDFA better, the visual simulation software is devised. The programs are composed of three parts: one is designed for simulating single channel operation and second for simulating multi-channel operation under steady state, the last part is designed for simulating the characteristics of multi-channel under dynamic state. All the works are based on the software, it is meaningful to predict the characteristic of EDFA in the design of EDFA.