The results show that,compared with symmetrical apodization method,the asymmetrical apodization method can avoid the disadvantage of the former method that widens the reflectivity bandwidth by reduction of apodization ratio,which meanwhile increases the time delay ripple. The left-shifted apodization method can reduced the time delay ripple by 43.5%,adjacent with the experimental result of 39.9%,while the refectivity spectrum is nearly unchanged.

Delay characteristics of cascaded chirped fiber Bragg gratings (CFBGs) have been theoretically analyzed. Delay ripple increases while the number of cascaded CFBGs increases, and also increases as the wavelength interval between neighbor CFBGs decreases.

The results show that,compared with symmetrical apodization method,the asymmetrical apodization method can avoid the disadvantage of the former method that widens the reflectivity bandwidth by reduction of apodization ratio,which meanwhile increases the time delay ripple. The left-shifted apodization method can reduced the time delay ripple by 43.5%,adjacent with the experimental result of 39.9%,while the refectivity spectrum is nearly unchanged.

The results show that,compared with symmetrical apodization method,the asymmetrical apodization method can avoid the disadvantage of the former method that widens the reflectivity bandwidth by reduction of apodization ratio,which meanwhile increases the time delay ripple. The left-shifted apodization method can reduced the time delay ripple by 43.5%,adjacent with the experimental result of 39.9%,while the refectivity spectrum is nearly unchanged.

Delay characteristics of cascaded chirped fiber Bragg gratings (CFBGs) have been theoretically analyzed. Delay ripple increases while the number of cascaded CFBGs increases, and also increases as the wavelength interval between neighbor CFBGs decreases.

The results show that,compared with symmetrical apodization method,the asymmetrical apodization method can avoid the disadvantage of the former method that widens the reflectivity bandwidth by reduction of apodization ratio,which meanwhile increases the time delay ripple. The left-shifted apodization method can reduced the time delay ripple by 43.5%,adjacent with the experimental result of 39.9%,while the refectivity spectrum is nearly unchanged.

The effect of the group delay ripple of the fiber grating is also investigated in the recirculating systems, and it is shown that the transmission distance is limited to 4 cycles (4×167.1km) in the loop with the power penalty fluctuation below 1.0dB.

Thus the group delay ripple should be reduced to allow for the wavelength drift of ±5GHz.

We describe the theory of the group delay ripple (GDR) generated by apodized chirped fiber gratings using the analogy between noisy gratings and superstructure Bragg gratings.

Dispersion compensator imperfections, such as multi-path interference, group delay ripple, insertion loss ripple and limited per-channel compensation bandwidth, place additional limitations on the achievable transmission distance and capacity.

In the second section we describe the techniques used to fabricate high performance dispersion compensation gratings as well as the theory of the primary defect of fiber grating dispersion compensation: group delay ripple (GDR).

The effect of the group delay ripple of the fiber grating is also investigated in the recirculating systems, and it is shown that the transmission distance is limited to 4 cycles (4×167.1km) in the loop with the power penalty fluctuation below 1.0dB.

Thus the group delay ripple should be reduced to allow for the wavelength drift of ±5GHz.

We describe the theory of the group delay ripple (GDR) generated by apodized chirped fiber gratings using the analogy between noisy gratings and superstructure Bragg gratings.

Dispersion compensator imperfections, such as multi-path interference, group delay ripple, insertion loss ripple and limited per-channel compensation bandwidth, place additional limitations on the achievable transmission distance and capacity.

In the second section we describe the techniques used to fabricate high performance dispersion compensation gratings as well as the theory of the primary defect of fiber grating dispersion compensation: group delay ripple (GDR).

The strain effect on fiber Bragg grating (FBG) wavelength, 3 dB bandwidth reflectivity and characterizatin of delay is experimentally studied. Change of the center wavelength and 3 dB bandwidth is linear with the strain, but the reflectivity decreases when the strain increases. Linearity of delay becomes better, root-mean-square deviation of delay ripple reduced and compensation lessens, when the strain increases.

The delay ripple of chirped FBG is analyzed in detail. A simple physical model and function of filter are set up about chirped FBG (CFBG). A numerical simulation of grating delay ripple has been done using SchrAo¨dinger equation and compared with experiment. The research shows that the system degradation depends on the period and amplitude of delay ripple. The period of CFBGs′ delay ripple is 0.01～0.1 nm indicated through a lot of experiments. The amplitude of delay ripple must be less than 15 ps in order...

The delay ripple of chirped FBG is analyzed in detail. A simple physical model and function of filter are set up about chirped FBG (CFBG). A numerical simulation of grating delay ripple has been done using SchrAo¨dinger equation and compared with experiment. The research shows that the system degradation depends on the period and amplitude of delay ripple. The period of CFBGs′ delay ripple is 0.01～0.1 nm indicated through a lot of experiments. The amplitude of delay ripple must be less than 15 ps in order to assure eye opening penalty less than 0.5 dB.

Delay characteristics of cascaded chirped fiber Bragg gratings (CFBGs) have been theoretically analyzed. Delay ripple increases while the number of cascaded CFBGs increases, and also increases as the wavelength interval between neighbor CFBGs decreases. A way to mitigate the effect, namely using 8-order Gaussian apodization when CFBGs are written is found.