| 摘要 |
An optical transport system has an optical transmitter and an optical receiver coupled to one another via an optical link having a plurality of transmission paths. The optical transmitter uses at least one of the transmission paths to transmit an optical-reference signal that enables the optical receiver to obtain (i) an optical local-oscillator signal that is phase- and frequency-locked to an optical-carrier frequency used by the transmitter for the generation of data-bearing optical signals and (ii) a clock signal that is phase- and frequency-locked to the clock signal used by the transmitter. The optical receiver then uses these signals to demodulate and decode the data-bearing optical signals in a manner that significantly reduces the complexity of digital signal processing compared to that in a comparably performing prior-art system. In various embodiments, a transmission path for the optical-reference signal can be established using any suitable dimension orthogonal to those occupied by the data-bearing signals, such as polarization, wavelength, or space.
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