
4
Self-coherent optical transport systems
Xiang Liu, Sethumadhavan Chandrasekhar,
and Andreas Leven
Bell Laboratories, Alcatel-Lucent, Holmdel, NJ, USA
4.1 INTRODUCTION
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 ...