Research And Design Of Erbium Doped Fiber Amplifier In Optical Transmission System

Optical fiber loss is a limiting factor in the application of high-speed optical networks.However,this loss can be compensated by various optical amplifiers.Raman amplifier and erbium-doped fiber amplifier Erbium Doped Fiber Amplifier(EDFA)amplifier are widely used in optical communication system.Compared with Raman amplifier,EDFA amplifies the signal at 1550 nm wavelength,and the fiber loss is the smallest.In addition,there is no pulse isolation problem in EDFA amplifiers.With the emergence of EDFA and other optical amplifiers,it is feasible to realize high bit rate in optical network applications.In this paper,a forward pump bipolar EDFA(working in C band 1525-1565 nm)based on gain flat filter gain flattening filter(GFF)is designed to evaluate the gain and noise coefficient of forward pumped EDFA in C band(1525-1565 nm).Amplification of spontaneous emission power variation and other performance parameters.The performance of EDFA can be completely characterized and optimized by using Optisystem and experimental platform.In recent years,there are more and more research on optical amplifiers.The amplifier needs to amplify many optical signals at the same time in a certain wavelength range.The main contents of this paper are as follows:1.The basic principle,composition,Giles model,performance index and the influence of various parameters on the gain of EDFA are analyzed.The pump power,erbium-doped fiber length,erbium-doped ion concentration,input signal power and input signal wavelength of erbium-doped fiber amplifier are analyzed by simulation model.It is concluded that the power is small and the gain does not change much.The gain decreases with the increase of signal power.The gain begins to appear at a certain value of the pump power(pump threshold)and continues to increase rapidly and saturate at a higher pump power value.With the increase of EDF feed fiber length to a certain length,it is observed that the gain increase gain reaches the maximum and begins to decrease with the increase of EDF length.The gain of the amplifier increases with the increase of the concentration of erbium-doped fiber,and then does not increase.As long as the pump power is close to its maximum,it is possible to obtain the same gain at different wavelengths.2.The reason of gain flatness is analyzed,and the simple optimization of gain flatness is completed by adding GFF gain flatness filter.The gain,gain flatness and noise of single pump bipolar EDFA multiwave input signal based on GFF and GFF based on optical communication simulation software are studied and simulated theoretically.The optimal length of feed fiber before and after is determined,and the flatness of output gain is optimized.For the bipolar simplex wave amplifier,The input signal optical power is-20 dBm,the signal optical power is 10.305 dBm,gain 30.229 dB after the first amplification;and the signal optical output power 27.682 dBm,gain increases to 47.607 dB,output noise 4.433 dB after two-stage amplification.High gain and low noise.For a bipolar multiwave amplifier,the optical power of the input multiwave signal is-20 d Bm.After the first stage amplification,the output signal power is 5.4762 dBm,the gain is 25.4762 dB;The output power of the signal after two-stage amplification is 22.964 dBm..The Average Gain increases to 42.954 dB,the maximum gain is 43.001 dB,and the minimum gain is 42.918 dB.The gain is flat.The noise curve is less than 4 dB.3.The performance of various optical amplifier semiconductor amplifiers Semiconductor Optical Amplifier(SOA),EDFA,Raman amplifier and hybrid amplifier(SOA+EDFA,EDFA +EDFA,Raman+EDFA)at 50 GHz frequency interval in 8 × 10 Gbps dense wavelength Division Multiplexing(Dense Wavelength Division Multiplexing(DWDM)system is studied.Simulation results show that SOA+EDFA provides better output power for a small amount of transmission distance.For longer distances,SOA+EDFA has more stable performance.SOA+EDFA has better eye diagram than EDFA+EDFA and Raman+EDFA,and the bit error rate is much better than EDFA+EDFA and Raman+EDFA hybrid optical amplifiers.As the fiber length increases from 10 km to 40 km,the system performance begins to decline,and the output power and Q factor decrease.Compared to Raman and EDFA,SOA has the maximum output power and good Q factor.4.Set up the experimental platform to realize the test.The optimum length of the two-stage feed fiber ratio before and after the single pump bipolar amplifier is determined,and the gain curve spectrum and noise coefficient of the system are measured.Finally,it is determined that the length of the bait fiber in the front and back stages is 1m 6m.The maximum gain can reach 40 dB.The gain flatness is about 1dB.Due to the experimental error,the noise is larger than that of 5dB.The optimization effect of gain flatness is obtained both in theory and in practice.