Tunable interchannel broad-band dispersion-slope compensation for 10-Gb/s WDM systems using a nonchannelized third-order chirped FBG

We demonstrate tunable dispersion-slope compensation using a single broad-band nonchannelized fiber Bragg grating. Tunability of the dispersion slope is achieved by stretching the grating, which has a third-order timedelay variation with wavelength, thereby causing a second-order variation in dispersion. Although this nonlinear dispersion characteristic causes some inherent mismatch between the grating and real fiber links, the induced errors are negligible in 10-Gb/s systems. Dispersion-slope tunability of ~65 ps/nm/sup 2/ is achieved using a grating with dispersion variation of up to 400 ps/nm over a 3.5-nm usable bandwidth. Using this grating, we show over 10-dB improvement in the worst-case channel in a 10-Gb/s return-to-zero system. Two gratings are cascaded in order to double the dispersion values that can be compensated by the grating.