Multi-channel 100-Gbit/s DQPSK data exchange using bidirectional degenerate four-wave mixing

We propose a simple approach to performing simultaneous multi-channel data exchange using bidirectional degenerate four-wave mixing (FWM) in a single highly nonlinear fiber (HNLF) assisted by optical filtering. Data exchange between two-channel 100-Gbit/s return-to-zero differential quadrature phase-shift keying (RZ-DQPSK) signals with a variable channel spacing is implemented with a power penalty of less than 4.2 dB at a bit-error rate (BER) of 10(-9). Moreover, simultaneous ITU-grid-compatible four-channel 100-Gbit/s RZ-DQPSK data exchange is demonstrated with a power penalty of less than 4.7 dB at a BER of 10(-9).