Research On Performance And Characteristics Of Hybrid PSA-EDFA Optical Amplifier System

At present,the transmission capacity and distance are mainly limited by amplifier's noise and optical fiber nonlinearity in long-haul communication systems.phase-insensitive amplifier(PIA),such as erbium doped fiber amplifier(EDFA)whose lowest noise figure is 3 dB,which is also the quantum limit.This means that when the signal is amplified,the signal-to-noise ratio is reduced.The noise figure of phase sensitive amplifier based on four-wave mixing can achieve 0dB,means noiseless amplification,which makes PSA have an important prospect in the field of optical fiber communication.However,when PSA is applied in WDM systems,the nonlinear crosstalk between channels is positively correlated with the gain,which seriously limits the practical application of PSA.In addition to the low-noise feature,high gian can be realized by hybrid PSA-EDFA with also low crosstalk.The overall performance of hybrid PSAEDFA is closely related to PSA,gain and noise figure.Performance of hybrid PSAEDFA can be optimized by selecting the system parameters reasonably.However,there are few studies on mixed PSA-EDFA.This paper conducts theoretical and experimental research on the overall noise of hybrid PSA-EDFA.The main research contents and results of this paper include:(1)The theoretical principle of phase sensitive amplification is systematically analyzed.Based on the coupled wave equation,the theoretical model of four-wave mixing and parametric amplification is derived,and the theoretical model of PSA is obtained by using the method of transmission matrix analysis.The noise theory of cascaded optical amplifier is also analyzed(2)The noise characteristics of copier-PSA were studied experimentally.The gain of PSA after achieved the parametric amplification based on the high nonlinear fiber,and a phase locked loop structure was used to maintain the stability of PSA performance,so as to obtain the PSA gain of 23.6dB.the PSA gain obtained is 5.6dB higher than the phase-insensitive parametric amplification gain At the same pump power.Under the same signal gain,compared with non-phase-sensitive parametric amplification,the signal optical SNR after PSA amplification is 4.8dB higher.(3)The noise characteristics of Hybrid PSA-EDFA are studied theoretically and experimentally.Theoretical analysis shows that the noise figure of hybrid PSAEDFA is closely related to the PSA gain,and the light amplification with high gain and low noise can be obtained by properly configuring the PSA gain in the Hybrid optical amplification system.In the experiment,the noise characteristics of Hybrid PSA-EDFA are studied by means of spectral measurement and electro-spectral measurement.It is found that the total noise figure of mixed PSA-EDFA decreased rapidly with the increase of PSA gain,and the low PSA gain(<10dB)could greatly reduce the total noise index.As measured in the experiment,when the total gain is 45.6dB,the total noise index of the system drops to 2.9dB when the PSA gain is 9dB,which is lower than the noise index limit of traditional optical amplification.