Method and apparatus for communicating a clock signal in a soliton optical transmission system
AssigneeNortel Networks Limited
InventorsKim Byron Roberts, Hanan Anis, Maurice S. O'Sullivan
Life of this patent
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Abstract
A sub-harmonic clock signal is provided in a series of soliton optical pulses that are transmitted at a given line rate in a soliton optical transmission system. The line rate defines time slots of equal duration. Each soliton optical pulse in every N time slots is modulated in a manner to make the pulse distinguishable from pulses in other time slots. The frequency of the sub-harmonic clock signal is equal to the line rate divided by N. This technique of providing a clock signal allows simple recovery of the clock signal using a PIN diode photo detector and a bandpass filter of appropriate bandwidth.
Claims17
An optical soliton transmission system for the transmission of optical soliton pulses and providing a clock signal via the optical soliton pulses comprising a transmitter and a receiver,
- wherein said transmitter comprises:
- an optical soliton pulse source for generating optical soliton pulses at a first rate, the first rate defining time slots of equal duration;
- and
- a modulator for modulating each optical soliton pulse in every Nth time slot in a distinguishable manner from optical soliton pulses in other time slots, such that the clock signal has a frequency equal to the first rate divided by N, where N is an integer greater than one;
- and wherein said receiver comprises:
- means for detecting said clock signal from the optical soliton pulses received from said transmitter, wherein said means for detecting includes a clock recovery circuit which operates at 1/Nth the speed of the first rate;
- and
- a demultiplexer for demultiplexing the optical soliton pulses into a number of streams of optical soliton pulses responsive to the detected clock signal, the number of streams being an integer multiple of the integer N.
A receiver for receiving optical soliton pulses arriving at a first rate from an optical fiber in a soliton optical transmission system comprising:
- means for recovering a clock signal from the optical soliton pulses, the clock signal having a frequency equal to the first rate divided by an integer N, wherein the integer N is greater than one, wherein said means for recovering includes a clock recovery circuit which operates at 1/Nth the speed of the line rate;
- and
- a demultiplexer for demultiplexing the optical soliton pulses into a number of streams of optical soliton pulses responsive to the recovered clock signal, the number of streams being an integer multiple of the integer N.
Dependencies are inferred from the claim text.