Study On The Characters And Applications Of Cascaded Fiber Gratings

Fiber gratings play an important role in optical communication system for its various applications in dispersion compensators, and filters designing. Especially, with the demand on increasing numbers and wavelength-range of wavelength-division-multiplexing channels, Fabry-Perot (F-P) cavity composed by cascaded gratings has become one of the hot topics during last few years.Based on coupled mode equations method, the reflective coefficient is the same as that obtained and verified through transfer matrix method. According to the general theoretical model of fiber gratings F-P cavity, mutual out-band time delay crosstalk for cascaded fiber gratings are theoretical derived and simulated. The results show that the time delay crosstalk can be reduced by improving the Side Mode Suppression Ratio and choosing the suitable cascaded length.According to the analytical results above, considering the filtering and time delay characteristics for chirp fiber bragg gratings (CFBG) with high reflectivity, a cascaded CFBG based dispersion compensators is analized. Therefore, the desired dispersion compensators are achieved with different compensation values in different wavelength range. Moreover, multi-bandpass and narrow-band as well as multi-channel comb filters are obtained by cascading fiber gratings. Compared with the available technique, our method performs such advantages, especially different compensation values are achieved in different wavelength range, and wavelength shifted can be tolerated.