System and method of high-speed transmission and appropriate transmission apparatus
AssigneeCisco Photonics Italy S.r.L.
InventorsPierluigi Franco, Giorgio Grasso, Matjaz Vidmar
Life of this patent
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Abstract
At a receiver a 20 Gbit/s soliton bit stream (20) is demultiplexed into two 10 Gbit/s bit streams (22a, 22b) using a 2-way splitter (6), a clock extraction circuit (4), and a pair of polarization insensitive amplitude modulators (8a, 8b) exhibiting positive chirp. The outputs of the modulators are fed to detectors (7a, 7b) via lengths (9a, 9b) of optical fiber exhibiting normal dispersion thereby producing bit streams (23a, 23b) with increased mark/space ratio and reduced timing jitter.
Claims10
Pulsed transmission system, comprising at least one transmission station for transmitting an optical signal at a transmission wavelength, at least one reception station, a fibre-optic line linking said at least one transmission station and said at least one reception station and at least one optical amplifier serially linked along said fibre-optic line, wherein said fibre-optic line has a positive overall chromatic dispersion at said transmission wavelength and comprises:
- a first optical conductor element, having a first chromatic dispersion at said transmission wavelength, the first optical conductor element comprising step-index fiber;
- and
- a chromatic dispersion compensating unit having a second chromatic dispersion at said transmission wavelength, said second chromatic dispersion being of opposite sign with respect to said first chromatic dispersion;
- wherein said at least one transmission station comprises a high speed optical pulse transmitter adapted to generate an RZ optical signal at said transmission wavelength, bearing a coded information at a preset frequency, said RZ optical signal comprising optical pulses of duration TFWHM, wherein:
- the ratio Tbit/TFWHM, between the inverse Tbit of said frequency and said duration TFWHM of the pulses, is higher than 6 and lower than 10, and
- said optical pulses are substantially free from chirp.
Optical pulse transmission method, comprising the steps of:
- emitting an optical signal at a transmission wavelength and at a preset frequency bearing a coded information;
- supplying the optical signal in an optical-fibre line having a chromatic dispersion and comprising a plurality of stretches of step-index fiber;
- compensating the chromatic dispersion of the signal in the optical-fibre line with a chromatic dispersion of the opposite sign, so as to achieve an overall positive dispersion for the optical signal;
- wherein said step of emitting comprises:
- generating a sequence of substantially chirp-free optical pulses at the transmission wavelength having a duration TFWHM the ratio Tbit/TFWHM, between the inverse Tbit of said preset frequency and said duration TFWHM of the pulses, being higher than 6 and lower than 10;
- and
- modulating said sequence of optical pulses with said coded information.
Dependencies are inferred from the claim text.