Research On Fiber Optical Parametric Amplifier And Its Application

With the rapid development of the optical communication technology for thirty years, people have put forward higher requirements for the speed and the stability of the communication network. This will lead to the further researches of optical communication system with larger transmission capacity and wider transmission range. In this case, the dense wave division multiplexing (DWDM) as the times require greatly improves the performance of the optical communication system. Meanwhile, this transmission technology with long and multi-channel characteristics needs an all-optical amplifier to match. Therefore, the study on properties and application of fiber optical parametric amplifier (FOPA) for optical communication is of great significance to the development of the future. This thesis focuses on theoretical and experimental researches on gain and applications of phase insensitive fiber optical parametric amplifier (PI-FOPA) and phase sensitive fiber optical parametric amplifier (PS-FOPA) based on highly nonlinear fiber (HNLF).The thesis firstly reviewed the research achievements obtained by domestic or foreign scholars in the field of FOPA and phase sensitive optical parametric amplifier, and the simulation and experimental system for PI-FOPA is established. The influences of signal power, pump power and wavelength on gain of PI-FOPA are analyzed. These research results provide an important basis for the research on non-degenerate cascaded PS-FOPA. The experimental system for non-degenerate cascaded PS-FOPA is established based on PI-FOPA. The influences of pump power and wavelength, the length of HNLF in phase insensitive amplifier (PIA) and phase sensitive amplifier (PSA) segment on gain of non-degenerate cascaded PS-FOPA are analyzed. These research results provide an important basis for the research on applications of non-degenerate cascaded PS-FOPA.To ensure non-degenerate cascaded PS-FOPA can be effectively applied to DWDM optical communication system, a power equalization scheme has been proposed for non-degenerate cascaded PS-FOPA based on dispersion compensation fiber (DCF). The simulation results show that when the length of DCF as a compensation that is 125 m and the length of single mode fiber (SMF) that work as a fiber patch cord inserted between PIA and PSA segment is 15 m, the power fluctuation of non-degenerate cascaded PS-FOPA for sixteen input signals has been decreased from 7.74 dB to 1.17 dB, and the gain bandwidth of non-degenerate cascaded PS-FOPA is broadened and approximately equal to 15 nm.Moreover, for optical frequency comb played a crucial role in DWDM optical communication system, the simulation researches on the application of non-degenerate PS-FOPA on optical frequency comb based on passive resonant cavity are achieved in this thesis. When the pump power is 33.5 dBm, the non-degenerate PS-FOPA can make the spectral flatness of optical frequency comb improve from 8.9 dB to 1.9 dB, and from 8.9 dB to 1.58 dB by PI-FOPA. But comparing to PI-FOPA, the non-degenerate PS-FOPA has larger gain. These research results provide a further basis that non-degenerate cascaded PS-FOPA can be used in DWDM optical communication system.The amplitude shift keying (ASK), as a basic modulation format used in optical communication system, the research on it based on PI-FOPA is significant. The 4-ASK signal generated with two ASK signals by PI-FOPA is achieved in this thesis. The influences of pump power, signal power and extinction ratio on the relative extinction ratio (REX) of 4-ASK signal are theoretically and experimentally investigated. The results indicate that the value of the input signal extinctionratio and pump power are important on the REX of 4-ASK signal, however, the input signal power has little influence on REX. These research results provide an important basis for the research on applications of FOPA to receiver of optical code division multiple access free space optics (OCDMA-FSO) communication system.For making the OCDMA-FSO communication system receiver to get rid of the complex structure limitation of fiber Bragg grating (FBG), and being convenient to change length of coding sequence in the electrical domain to adapt to complex and fast-changing weather conditions for OCDMA-FSO communication system, a new receiver with PI-FOPA/non-degenerate cascaded PS-FOPA for OCDMA-FSO communication system is proposed for the first time in this thesis. The noise tolerance (NT) is derived and set as the performance index in receiver for the OCDMA-FSO communication system. The influences of the EX and power of the input signal, the EX and power of pump on the NT are analyzed. The simulation result indicates that he NT can achieve an improvement of about 18.77 dB and 21.65 dB respectively by PI-FOPA/non-degenerate cascaded PS-FOPA when the pump power is up to 5 W and length of coding sequence is up to 256.In the end, we summed up the total content of the thesis and put forward to the shortcomings and improvement measures.