Font Size: a A A

Numerical Study On Optical Soliton Propagation System With 40Git/s In Photonic Crystal Fibers

Posted on:2009-03-09Degree:DoctorType:Dissertation
Country:ChinaCandidate:J WangFull Text:PDF
GTID:1118360245488131Subject:Detection and processing of marine information
Abstract/Summary:PDF Full Text Request
The photonic crystal fiber (PCF), as a recent version of fibers with many novel characteristics, has overcome the optical limitations of the traditional fiber and led to the widening of its applications. It also provides a possible solution to some technical obstacles in the development of traditional fiber. For example, the soliton transmission could be achieved easily, using the changeable dispersion and large nonlinear effects of the photonic crystal fiber. And with the small bending loss and the capability of the high-power transmission, the PCF could be helpful for some special application area, like deep sea communications. How to achieve the long-distance and large-capacity communications with great speed has been one of the key problems in the deep-sea communications and information transmission of deep-sea exploration. In the thesis, numerical simulation of the 40 Gbit/s soliton transmission system in the PCF was investigated, with the hope of giving some possible theoretical solutions for development of ultra-long-distance communication and large-capacity communication system, hence to satisfy the urgently demands for the upgrading of the communication system in the deep-sea exploration and deep-sea communications.The thesis begins with a detailed review of the relevant developments for the ocean communications, including underwater acoustic communication, underwater communication cable and optical soliton communication, with the focus on the status, advantages and development prospects of the optical soliton communication in the PCF. It has been suggested that the system with newly developed PCF as the transmission medium and the optical soliton as the carrier could be one of the best ways for future deep-sea communications. In the thesis, the nonlinear Schr(o|¨)dinger equation has been used for the analysis of 40Gbit/s soliton communication system using the split-step Fourier method. The system performance is numerical simulated based on the soliton transmission and chirps with the influence resulted from various effects. The coupled nonlinear Schr(o|¨)dinger equations for the femtosecond soliton self-trapping is numerical calculated by the split-step Fourier method. The possibility of the polarization multiplexing soliton communications system in PCF has also been analyzed. The author's main contributions are concluded as following.1) Based on the interaction mechinese between light and the fiber, the method of the chirp research has been well established. With this method, the conditions for soliton forming in the PCF have been derived. It is found that three-order chromatic dispersion produces chirp in the femtosecond soliton transmission. The resultant total chip has been numerically calculated with the consideration of the joint effects from the group velocity dispersion (GVD), the self-phase modulation(SPM), the third-order dispersion(TOD), the self steepening (SS) and the intrapulse stimulated Raman scattering (ISRS). From the evolution of the chirp, we explain the physical mechanism of those effects and how each one acts on the soliton transmiting. We also derive the chirp produced by the cross-phases modulation effect and analyze the characteristic of the chirp evolution. As a result of this analysis, the property of the polarized multiplexing soliton transmission is opened out.2) Based on split-step Fourier method, a set of programs have been made for the numerical simulations of single pulse transmission in the PCF, the maximum transmission distance and system eye pattern of the 128bit pulse array, the on-line synchronal modulation and the sliding frequency filter compensations system.3) The transmission characteristics of the single soliton in the PCF have been studied. The obtained results have offered a valuable simulation for the design of the soliton transmission system in the PCF. In this thesis, the numerical calculations have been made for the transmission conditions of the ideal soliton, and the analysis of the effect resulted from the TOD, SS, ISRS and the initial chirp in the soliton transmission. The soliton actual transmission has been simulated with various effects active at the same time. With the numerical calculation of the pulse transmission in the PCF, it has been shown that the pulses could be compressed, and a narrow pulse with the high compression ratio and the small substrate base could be achieved in PCF.4) The 40Gbit/s soliton transmissions system in the PCF has been numerical simulated. The property of the system has been evaluated using bit error ratio and eye pattern. The special attention has been paid to the varying of maximum transmission distance and the eye pattern with PMD, GVD and duty cycle in the system. Based on the analysis of the chirps produced by various effects, we propose the two compensation methods to optimize the property of the system. They are on-line synchronal modulation and the sliding frequency filter, it has shown that both of them worked very well.5) Based on the coupling nonlinear Schr(o|¨)dinger equation, the soliton self-trapping and its generation threshold have been investigated using the split-step Fourier method, at the presence of the high-order nonlinear and the high-order dispersion. It has been found that the initial femtosecond soliton pulse could be trapped due to the higher mode birefringence of the PCF. The possibility of forming a polarized multiplexing soliton system in PCF has also been discussed.
Keywords/Search Tags:chirp evolution, optical soliton, synchronous modulation, sliding frequency, photonic crystal fiber
PDF Full Text Request
Related items