All-optical chromatic dispersion monitoring of a 40-Gb/s RZ signal by measuring the XPM-generated optical tone power in a highly nonlinear fiber

We experimentally demonstrate an all-optical chromatic dispersion (CD) monitoring technique potential for ultrahigh-speed systems. A monochromatic continuous wave probe is coupled with the tapped-off data signal into a highly nonlinear fiber. An optical tone that is sensitive to CD is generated near the probe wavelength due to the cross-phase modulation effect and is used for CD monitoring. The monitoring window is /spl plusmn/42 ps/nm for 40-Gb/s return-to-zero systems. This monitoring technique is simple and needs no modification at the transmitter.