Patent ID: 8649687
Filing Date: 2014-02-11
Classification: H04B,H04J

Abstract:
1. A method in a transmitting node for transmitting data information in a modulated optical carrier signal over an optical channel in an optical communications network to a receiving node, the method comprising: receiving a data signal indicating the data information to be transmitted, extracting drive signals from the received data signal, including a first, second, third, fourth, fifth, and sixth drive signal, synchronizing said drive signals, generating a carrier signal, splitting the carrier signal into two separate signals, a first signal fed to a first modulator for performing In-phase/Quadrature modulation and a second signal fed to a second modulator for performing In-phase/Quadrature modulation, synchronizing the first signal with the second signal, modulating the first signal in the first modulator by applying the first and second drive signals to the first modulator, and modulating the second signal in the second modulator by applying the third and fourth drive signals to the second modulator, wherein a quadrature component in the first signal and in the second signal are phase shifted in a phase shifter, modulating the modulated first signal in a third modulator for polarisation modulation by applying the fifth drive signal to the third modulator, and modulating the modulated second signal in a fourth modulator for polarisation modulation by applying the sixth drive signal to the fourth modulator, wherein third modulator is driven by the fifth drive signal and the fourth modulator is driven by the sixth drive signal, combining the polarisation modulated first signal from the third modulator with the polarisation modulated second signal from the fourth modulator, and transmitting the combined signal over the optical channel to the receiving node.