Tunable 503 ns optical delay of 40 Gbit/s RZ-OOK and RZ-DPSK using a wavelength scheme for phase conjugation to reduce residual dispersion and increase delay

We demonstrate a method for a tunable optical delay element that allows for minimal residual dispersion and double the relative delay. A tunable delay of 503 ns for 40 Gbit/s return-to-zero on-off keying and return-to-zero differential phase-shift keying is shown with a reduction in residual dispersion of approximately 95%.