Research And Implementation Of Gain Flatness Characteristics Optimize Of Erbium-doped Fiber Amplifiers Based On GFF

With the rapid development of the modern optical communication system, Erbium-doped fiber amplifier(EDFA) with its characteristic which can be direct amplification of optical signals are widely used, is a very important part. In recent years due to the increasing popularity of dense wavelength division multiplexing systems, need an amplifier of a certain wavelength range can be many simultaneous amplification of optical signals. But because the effect of the main material of erbium-doped fiber amplifier——erbium ions, gain of the amplifier on a different wavelength optical signals are unevenly distributed, that means a group of the same power but different wavelength signals through the same amplifier the output optical signals' power will be different. And after a cascade of multiple amplifiers, inhomogeneous distributions of gain are more and more obvious. This will cause the distortion of the transmitted signal, and increased error rate of optical signal. So the flatness of erbium doped fiber amplifier is a research focus in the field of optical communication, and the research has stronger theoretical basis and practical significance.The work of this paper is based on a company of Wuhan actual project, study for the gain flatness of erbium- doped fiber amplifier in WDM system, the main research contents are as following:1. The basic principle of EDFA are analyzed theoretically, includes transition of erbium ions, the working principle and basic structure of EDFA. Describes the basic concepts and significance of evaluation of EDFA system performance indicators, including the gain, noise figure, bandwidth, gain flatness, saturated output power and so on. Simulate the EDFA system to find the relationship between the gain and the erbium-doped fiber(EDF) concentration, length of erbium-doped fiber, signal power, pump power and signal wavelength when the input signal is single wavelength optical.2. Focuses on the gain flatness of erbium-doped fiber amplifier, Analysis of the causes of uneven gain, simulation and Experiment study on the factors affecting the gain flatness. When the input signals are multi-wave signals, Simulate the EDFA system to find the relationship between the gain flatness and length of erbium-doped fiber(EDF), signal power, pump power. Through a simple optimization of adjusting parameters to achieve the gain flatness.3. Insert a gain flatness filer in EDFA to optimize the gain flatness, used the simulation software OptiSystem to design a 980 nm two-stage cascaded EDFA optical diagram. Determining parameters of various optical devices, designed by method of multiple iterations GFF loss spectrum, and improved the method of iteration. And load the designed to verify the correctness of the design. Finally the physical and tests to verify the correctness of the design, and the gain optimal results have been achieved.