Research On Performance Optimization Technology Of Er/Yb Co-Doped High Power Fiber Amplifier

With the increasing demand of human society for communication,information interaction technology has become more and more important.In the traditional communication network,the communication technology mainly based on electrical signals has been gradually eliminated,and replaced by optical fiber communication networks with laser signals as the main method.It has the advantages of high confidentiality,strong anti-interference,and good information transmission quality.It has a wide range of application prospects and market value.However,it has been found that with the increase of communication distance,the problem of power attenuation and even cut-off distortion will occur during the transmission of laser signals.The invention and application of optical amplifiers easily solve the above problems.However,in the current stage of the development of optical fiber communication networks,in order to increase the user's demand for network bandwidth and increase the overall network communication capacity,traditional fiber amplifiers have exposed problems such as difficulty in increasing output power,high output noise,and poor gain flatness.Based on the structural characteristics of the Er/Yb co-doped fiber amplifier,this thesis conducts research on multi-point pumping technology and gain flattening technology,and optimizes the high-power fiber amplifier from the theoretical and experimental aspects.The main work is as follows:1)Aiming at the problem of increasing the output power of fiber amplifiers,this thesis proposes a multi-point side melt cone pump coupling technology through a comprehensive analysis and comparison of pump technologies,and measures and analyzes the pump coupling efficiency of this structure.The Optisystem optical design software was used to carry out the simulation experiment on the multi-point side-pumped Er/Yb co-doped fiber amplifier,and the technology was optimized and improved according to the simulation data.2)Improve the stability of the pump source,thereby reducing the output noise of the fiber amplifier.In this thesis,the drive control system of the pump laser is designed,and the combination of current feedback and power feedback is used to stabilize the output of the pump source.DHM905 chip and ADN8830 chip are used to design the circuit of constant current source and temperature control unit,and a protection circuit for the pump laser is added to the design.3)Aiming at the problem of poor output gain flatness of the fiber amplifier,this thesis analyzes and compares two types of typical methods to achieve gain flatness,and conducts research on gain flattening technology based on the polarization-maintaining fiber ring mirror structure.The filtering characteristics and principles of the fiber loop mirror are studied and analyzed.The parameters of the polarization maintaining fiber and the polarization controller in the fiber loop mirror structure are optimized by using matlab software,and a gain flat filter for the fiber amplifier in this thesis is designed.4)The overall fiber amplifier is structured.With an input signal optical power of 1m W and a total pump power of 14 W,the amplifier obtains a gain of 36.7d B and an output power of 4.68 W.The overall output gain flatness is within the wavelength range of 1534nm-1560 nm.Both are controlled within ± 1.3d B.