3-bit/symbol optical data format based on simultaneous DRZ, DPSK and PolSK orthogonal modulations.

We propose a novel 3-bit/symbol optical data format based on simultaneously modulating dark-return-to-zero (DRZ), differential-phase-shift-keying (DPSK) and polarization-shift-keying (PolSK) on the same optical carrier. Transmission performance is investigated. The proposed data format has a more compact spectrum when compared with other modulation schemes (at the same data rate), such as return-to-zero (RZ), DPSK and PolSK. It is also more tolerant to phase noise when compared with optical-differential-quadrature-phase-shift-keying (ODQPSK).