tailieunhanh - Optical Fiber Communications and Devicesan incorrectly Part 4

Tham khảo tài liệu 'optical fiber communications and devicesan incorrectly part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Effects of Dispersion Fiber on CWDM Directly Modulated System Performance 65 will occur. At this length L2 I C I 1 C2 Cl becomes zero and the pulse becomes unchirped. We define this situation as optimal. Finally with further propagation the fast and the slow frequency components will tend to separate in time from each other and pulse broadening will be observed. On the other hand the SPM alone leads to pulse chirping with the sign of the SPM-induced chirp being opposite to that induced by anomalous GVD. In Figure ll the leading edge of the pulse becomes red-shifted and the trailing edge of the pulse becomes blue-shifted. If the effects of anomalous dispersion were present with the chirp induced by SPM some pulse narrowing would occur. This means that the effect of SPM counteracts GVD. Fig. ll. Input left and output right pulse shape and chirp. The effect of GVD on the pulse propagation depends mainly on whether or not the pulse is chirped the laser injection pulse shape del Rio 2010 and also on the fiber SPM Self Phase Modulation Hamza M. Y. Tariq S. Chen L. 2006 2008 . With the correct relation between the initial chirp and the GVD parameters the pulse broadening which occurs in the absence of any initial chirp will be preceded by a narrowing stage pulse compression . On the other hand the SPM alone leads to a pulse chirping with the sign of the SPM-induced chirp being opposite to that induced by anomalous GVD. This means that in the presence of SPM the GVD induced pulse-broadening will be reduced in the case of anomalous while extra broadening occurs in the case of normal GVD. 4. Enhancing the performance of systems using negative and positive dispersion fibers In this section we study that the transmission performance depends strongly on dispersion fiber and DML output power. We demonstrated that systems using SMF fibers can achieve a good performance if the DML output power is properly chosen. Finally we have found a mathematical expression that make an .