All-optical modulation format conversion from NRZ-OOK to RZ-M-ary PSK based on fiber nonlinearity

We propose an all-optical modulation format conversion scheme from non-return-to-zero on-off-keying (NRZ-OOK) to return-to-zero (RZ) M-ary phase-shift-keying (PSK) based on fiber nonlinearity. The proposed conversion scheme is numerically investigated and experimentally demonstrated with the error-free operation of NRZ-OOK/RZ-quadrature PSK (QPSK) conversion at 10.7 Gsymbol/s.