Optical clock recovery
AssigneeBritish Telecommunications public limited company
InventorKevin Smith
Life of this patent
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Abstract
A system for recovering a clock from an optically encoded signal uses a mode-locked laser. A modulator is connected in common with the laser cavity of the laser and a transmission path applies the input optically encoded signal to the modulator. The modulator in response to the optically encoded signal modulates the phase and/or amplitude of light in the laser cavity thereby locking the phase and frequency of an output pulse stream to the timing wave of the optically encoded signal. In a preferred example, the modulator is a non-linear optical modulator used for cross-phase modulation (XPM) of the light in the laser cavity.
Claims24
A system for recovery of a clock from an optically encoded signal comprising:
- a mode-locked laser including a cavity;
- an optically controlled optical modulator in the optical path of the optical cavity of the mode-locked laser;
- means for applying an optically encoded input signal to the optically controlled optical modulator;
- and
- means for outputting an optical pulse stream from the system;
- wherein the optically controlled optical modulator in response to the optically encoded signal modulates the phase and/or amplitude of light in the laser cavity thereby locking the phase and frequency of the output pulse stream to a timing wave of the optically encoded signal.
A method of recovering a clock from an optically encoded signal, including the steps of driving an optically controlled optical modulator in a mode-locked laser with the optically encoded signal and thereby generating in the laser a pulse train locked in phase and frequency to a timing wave of the optically encoded signal and outputting the pulse train.
A mode-locked laser system comprising:
- a fibre laser;
- means for pumping the fibre laser;
- an optically controlled optical fibre modulator connected in the path of an optical cavity of the fibre laser and connected in common with an optical transmission path for a driving signal;
- and
- means for outputting an optical pulse stream from the laser;
- wherein the driving signal modulates the phase and/or amplitude of light in the optical path of the laser cavity, thereby mode-locking the laser.
Dependencies are inferred from the claim text.