Optimization Design And Analysis Of Gaussian Doped Four Line Polarization Mode Fiber Amplifier

Few-mode erbium-doped fiber amplifier has been paid more and more attention with the increasing demand for transmission capacity and the limitation of the fragrant limit faced by single-mode fiber.In the few-mode fiber,each mode of the optical fiber can become an independent transmission channel for transmitting information.However,these different channels may have great differences in gain because of the different modes.As a consequence,it is difficult to ensure the quality of the signal transmitted by the whole transmission system.As a consequence,it is of practical value to make the differential mode gain(DMG)as small as possible on the premise of ensuring that the few-mode erbium-doped fiber amplifier(EDFA)has sufficient gain multiple.At present,many scholars have adopted erbium ion optimization design for the mode gain equalization of EDFA to reduce the DMG in EDFA.However,these design schemes have some defects.A four-wire polarization mode erbium-doped fiber amplifier(4LP-EDFA)based on two segments of erbium-doped fiber with different Gaussian morphology is designed based on this.Moreover,the parameters of the two-segment erbium-doped fiber are optimized by an improved adaptive mutation genetic algorithm.The specific contents are summarized as follows:(1)This study analyzes and summarizes the current research results on the optimization of erbium ion distribution in EDFA.In addition,it puts forward a new design idea on the basis of summary and analysis;(2)The amplification principle of linear polarization mode fiber is studied under the theoretical model of optical fiber.The gain and noise performance of single-segment uniformly doped 4LP-EDFA with different fiber length,pump power,signal power and erbium ion doping concentration are analyzed based on the power transmission equation of EDFA signal light and pump light.The results show that there is a large DMG in single-segment uniformly doped 4LP-EDFA.In the single doped 4lp-edfa,the increase of fiber length,signal power and erbium ion concentration will lead to the increase of Noise figure(NF),while the increase of pump power will reduce NF;(3)The improved genetic algorithm is used to optimize the 4P-EDFA formed by the cascade of two erbium-doped fibers with different Gaussian topographies.The cascaded4LP-EDFA can obtain a mode average gain of about 24.52 dB in the four-mode signal at the same time after optimization and the DMG is about 0.09 dB;(4)The gain characteristics of the cascade 4LP-EDFA designed when the length of two sections of optical fiber,the position of erbium ion Gaussian doping center,the half width of Gaussian doping,the input power of pump light,the input power of signal light,the wavelength of signal light and the peak concentration of erbium ion are analyzed when other conditions remain unchanged.As a result,these parameters can make the average gain of cascade 4LP-EDFA greater than 24 dB and DMG less than 1dB in a certain variation space when the length of two sections of optical fiber,the position of Gaussian doping center of erbium ions,the half width of Gaussian doping,the input power of pump light,the input power of signal light,the wavelength of signal light and the peak concentration of erbium ions are used as control variables alone.