Raman Effect On The Evolution Of Polarization In Law-Birefringence Fiber

In low birefringence fiber, by solving the coupled nonlinear Schrodinger equations containing the Raman effect for satisfying right-and left-handed circularly polarized light in the quasi-CW case, the relationship between the effective polarization beat length and changes of input power have been studied emphatically in low- and high input power situation considering the Raman effect or not, and the normalized power and the phase difference analytic solutions have been obtained. Using the analytic solutions, the expressions of ellipticity and azimuth angle have been deduced and the influences of Raman effect and the transmission distance on the polarization state evolution have been researched, the relationships of ellipticity and azimuth angle with input power were described by using the phase plane method. The results show that the polarization state evolution cycles of the incident light can be changed and meanwhile the transmission distance of the incident light also can be changed due to Raman effect, regardless of the polarization of the incident light was along the slow axis or along the fast axis; the transmission distance is the main factor that affect the stability of polarization, the polarization state evolution cycles of ellipticity and azimuth angle can be changed and the oscillation amplitude also can be changed for the low birefringence fiber in the transmission process.The paper consists of three parts, preface, main body and conclusion. The preface introduced the research background and research significance, etc. Main text have two parts:the theoretical derivation and process analysis of Raman effect on the polarization state in low-birefringence fiber are briefly introduced in first part and second part, finally has carried on the summary. The results show that the polarization state evolution cycles of the incident light can be changed and meanwhile the transmission distance of the incident light also can be changed due to Raman effect, the transmission distance is the main factor that affect the stability of polarization, the polarization state evolution cycles of ellipticity and azimuth angle can be changed and the oscillation amplitude also can be changed for the low birefringence fiber in the transmission process.