The Study of Modulation Instability in Optical Fiber Communication
|School||Southwest Jiaotong University|
|Course||Communication and Information System|
|Keywords||Optical fiber communication Modulation instability (MI) Self-phase modulation (SPM) Cross-phase modulation (XPM) Dispersion Management (DM)|
Modulation instability (MI) is a fiber optic communication system is a very common and important physical phenomena, it is caused by the interaction between the dispersion (or diffraction) and nonlinear instability of the light field. MI performance for the generation of spectral sidelobes in the frequency domain, the performance for the continuous or quasi-continuous light split into a series of ultrashort pulses in the time domain. Of great help the MI research to improve the optical communication system performance, research ultrashort pulses and optical soliton communication and other fields. The downside is that the modulation instability of the limitations of the transmission system, may result in undesirable signal amplitude modulation, limiting the output power of the system, resulting in higher costs for the system is running, it is necessary to study the MI. Firstly, brief MI status and significance of research; the next light pulses in optical fibers to meet the non-linear Schrodinger equation using traditional linear stability analysis, the the modulation instability caused by the SPM and XPM the sexual ground state gain do analysis and research; then at the same time consider the two to four order and about three or four cases of non-linear coefficient to study the phenomenon of optical fiber in MI, and numerical simulation; dispersion management (DM ) system modulation instability analysis and research, some conclusions, played a certain theoretical reference to the role of long-distance, high-capacity communication system design of dispersion management. The study results show that: the third-order dispersion instability gain spectrum; when certain conditions are met, due to the impact of the fourth-order dispersion, MI can occur in two spectral regions; the positive quintic nonlinear strengthened MI, the gain spectrum wider, larger peak negative quintic nonlinearity is weakened MI; When the incident power is small, five nonlinear modulation instability is not obvious, indicating when the incident power is very, ignoring non-linear five nonlinear terms, it is reasonable to sexual Schrodinger equation, with the increase of the incident power, the five nonlinear MI, growing, and ultimately reduce the modulation instability occurs incident power range; with the spectrum width of the increase in the distance MI gradually decreases, the gain spectrum of the amplitude will be gradually reduced: the dispersion management system, dispersion management FIG intensity increases, the gain generated in the MI process the greater the inhibition, the greater the path average dispersion, inhibition of the gain generated by the MI process more obvious.