High spectral-efficiency 100Gbit/s transmission using DRZ, DQPSK, and PoISK three dimension orthogonal modulation

We propose and demonstrate a new 4-bit/symbol optical data format based on simultaneously modulating dark return-to-zero (DRZ), differential quadrature phase-shift keying (DQPSK) and polarization-shift-keying (PoISK) for 100Gbit/s applications. Through numerical simulation, we show the differential tolerance of the three dimension modulation format toward polarization-mode dispersion (PMD) and chromatic dispersion. The receiver sensitivities of three different combined modulation formats, with those of DRZ, DQPSK and PoISK, are compared respectively, while extinction ratio of DRZ is changed. The proposed three dimension orthogonal modulation format has a more compact spectrum and is more tolerant to phase noise compared with DQPSK for 100Gbit/s transmission.