Patent ID: 6411415
Filing Date: 2002-06-25
Classification: G02F,H04B,H04L

Abstract:
Optical transmission system comprising a transmitter for transmitting optical pulses via an optical transmission medium to a receiver, the receiver comprises optical clock recovery means for generating a sequence of optical pulses with a frequency related to a pulse frequency of the optical pulses received from the transmission medium, the optical clock recovery means comprises an optical amplifier having its input coupled to its output via a feedback loop, said feedback loop comprises a non linear element, the optical clock recovery means comprises injection means for injecting the optical signal received from the optical transmission medium into the feedback loop, characterized in that said non linear element comprises a four port coupling element, two ports of the coupling element being included in the feedback loop and two ports being included in a secondary loop, the coupling element being arranged for coupling a first optical signal into a first branch of the secondary loop and for coupling a second optical signal into a second branch of the secondary loop, the secondary loop being arranged for causing signal level dependent interference between the first and second optical signal when re-entering the coupling element.