Clock recovery circuit and method for optical receiver

An optical receiver comprising means for converting a received signal in the optical domain to a digital signal in the electrical domain, said digital signal comprising a clock signal and a high-frequency jitter component due to polarisation scrambling in the optical domain, said optical receiver further comprising a clock recovery circuit comprising:

• a first clock recovery sub-circuit adapted to generate a first auxiliary clock signal with said high-frequency jitter component at least partly removed,
• a second clock recovery sub-circuit adapted to generate a second auxiliary clock signal still comprising said high-frequency jitter component,
• a phase comparator connected with the first and second clock recovery sub-circuits and adapted to compare respective phases of the first and second auxiliary clock signals to produce a high-frequency jitter signal depending on a phase difference between the first and second auxiliary clock signals, and
• a phase modulator connected with the first clock recovery sub-circuit and the phase comparator and adapted to modulate a phase of the first auxiliary clock signal with the high-frequency jitter signal to generate a recovered clock signal.

A method of recovering a clock signal from a digital signal comprising the clock signal and a high-frequency jitter component due to polarisation scrambling in the optical domain, said method comprising the steps of:

• generating from the digital signal a first auxiliary clock signal with said high-frequency jitter component at least partly removed,
• generating from the digital signal a second auxiliary clock signal still comprising said high-frequency jitter component,
• comparing respective phases of the first and second auxiliary clock signals to produce a high-frequency jitter signal depending on a phase difference between the first and second auxiliary clock signals, and
• modulating a phase of the first auxiliary clock signal with the high-frequency jitter signal to generate a recovered clock signal.