Self-Coherent Optical Transport Systems
01 January 2008
Self-coherent optical transmission based on differential phase-shift keying (DPSK) and direct detection [1-4] has emerged as an attractive vehicle for supporting high-speed optical transport networks by offering lower requirements on optical signal-to-noise ratio (OSNR) and higher tolerance to system impairments such as fiber nonlinear effects and coherent crosstalk, as compared to traditional on-off-keying (OOK) based transmission. Multilevel DPSK formats such as differential quadrature phase-shift keying (DQPSK) additionally offer high spectral efficiency and high tolerance to chromatic dispersion (CD), polarization-mode dispersion (PMD), and optical filtering, particularly when polarization-division multiplexing (PMUX) is also applied.