CN1447537A - Non-return to zero code fiber optic transmission system and dispersion compensation process - Google Patents
Non-return to zero code fiber optic transmission system and dispersion compensation process Download PDFInfo
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- CN1447537A CN1447537A CN02107653A CN02107653A CN1447537A CN 1447537 A CN1447537 A CN 1447537A CN 02107653 A CN02107653 A CN 02107653A CN 02107653 A CN02107653 A CN 02107653A CN 1447537 A CN1447537 A CN 1447537A
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Abstract
A dispersion compensator is added before and after the transmission link of the traditional non-return to zero code fiber optic transmission system composed of the laser, the modulator, the transmission link and the receiver in sequence. The prepositional dispersion compensator adjusts the waveform of the NRZ optical signal output from the modulator and broadents it to the quasi-continuous light in order to restrain nonlinear effect. The postpositional dispersion compensator compresses the quasi-continuous light output from the transmission link symmetrically in order to recover the NRZ optical signal within tolerance of dispersino in order to be received by the receiver. The invention is suitable to different kinds of optical fiber to realize super long distance transmission in undersea communication or in land communication.
Description
Technical field
The present invention relates to the Optical Fiber Transmission field, more particularly, relate to and a kind ofly can be applied to extra long distance nonreturn to zero code (NRZ) fiber optic transmission system and the dispersion compensation method thereof that submarine communication is communicated by letter with land.
Background technology
Nonreturn to zero code is one of coding of extensively adopting of present optical transmission system, it possess skills maturation, be widely used, characteristics such as cost is low.
Traditional non-return to zero code fiber optic transmission system as shown in Figure 1, the continuous wave of single longitudinal mode (CW) laser 1 output light signal is to intensity modulator 2, data-signal waiting for transmission is attached on the light carrier by modulator 2, the light carrier that has data-signal is a standard N RZ light signal, this signal is directly inputted to transmission link 4, transmit and arrive receiver 5, data-signal is recovered by receiver 5, reaches the purpose of signal transmission.Wherein the structure of transmission link 4 is made up of the optical fiber 41, image intensifer 42 and the link dispersion compensator spare 43 that connect successively as shown in Figure 3, and chromatic dispersion is reached in the dispersion tolerance scope of transmission signals by approximate full remuneration.But because noise and nonlinear effect be to the influence of transmitting optical signal quality, the without electronic relay transmission range of this structure is limited in 500-600km.
Owing to there is above-mentioned restriction, in order to guarantee that bit error performance meets the demands, every transmission 500-600km must carry out the regeneration of electricity, dwindle the deterioration that the optical amplifier repeaters spacing can the relieving system signal to noise ratio, the transmission range of without electronic relay is prolonged, but frequent light is put relaying and can be made that construction, the maintenance cost of system is too high and be not accepted.The regeneration of electricity not only increased system cost, the professional speed that provides has been provided, and influenced the professional transparency, upgradability.Along with development of Photonic Network and the increase in demand that reduces cost, improves service flexibility, the extra long distance transmission technology becomes research emphasis.
The key of extra long distance without electronic relay transmission is to reduce the influence of noise and nonlinear effect, improve the signal to noise ratio and the error rate of transmitting optical signal, adopt the RAMAN image intensifer, not only can reduce the launched power of system, thereby reduce the influence of nonlinear effect, and can reduce the noise of image intensifer, improve Optical Signal To Noise Ratio, this technology has been successfully applied to transmission market, seabed at present, and some special occasions on land also have certain applications.The deficiency of RAMAN optical amplifier technology originates from its amplification principle, it utilizes the nonlinear effect in the optical fiber: be excited the RAMAN scattering, the efficient of amplifying is very low on the one hand, the cost height, amplification performance is relevant with applied environment on the other hand, thereby the configuration difference of different system, cause and build and the maintenance complexity, influenced its large-scale application.
Improving another effective ways that transmit the Optical Signal To Noise Ratio and the error rate in the optical fiber is to improve light wave power, but the raising of power can cause the accumulation of nonlinear effect, has limited the prolongation of transmission range.In order to overcome the influence of nonlinear effect, coding techniques (NRZ etc.) becomes the focus of laboratory research, and some companies have also released the system of commercialization, and this technology is compared with NRZ sign indicating number technology, the modulation technique complexity, and cost is higher.
In order to reduce system cost, people have studied the relation of chromatic dispersion and nonlinear effect, dispersion management technique has been proposed, utilize the combination of different optical fiber (abbe number, chromatic dispersion gradient and optical fiber effective area etc.), reduced the nonlinear effect accumulation of system effectively, this technology has proposed higher requirement to laying optical fiber, and is not suitable for and lays the fibre system of finishing.
Summary of the invention
The technical problem to be solved in the present invention is, above-mentioned defective at prior art, provide a kind of and can be applied to extra long distance non-return to zero code fiber optic transmission system and the dispersion compensation method thereof that submarine communication is communicated by letter with land, can suppress nonlinear effect effectively, be applicable to different types of optical fiber.
Technical program of the present invention lies in, front and back at the transmission link of traditional non-return to zero code fiber optic transmission system is set up preposition dispersion compensation device and rearmounted dispersion compensation device respectively, wherein said preposition dispersion compensation device is regulated the waveform of the NRZ light signal that described modulator is exported, and its broadening become the class continuous light, to realize inhibition to nonlinear effect; And the class continuous light that described rearmounted dispersion compensation device is exported described transmission link carries out the symmetry compression, to realize the recovery to the NRZ light signal, makes it be received machine in the dispersion tolerance scope and receives.
In non-return to zero code fiber optic transmission system of the present invention, described preposition dispersion compensation device equate with the absolute value of the dispersion measure of rearmounted dispersion compensation device and opposite in sign, chromatic dispersion gradient also to be absolute value equate and opposite in sign.
In non-return to zero code fiber optic transmission system of the present invention, described transmission link is made up of optical fiber, image intensifer and link dispersion compensator spare, comprises four kinds of compound modes: connected successively by optical fiber, link dispersion compensator spare and image intensifer; Connect successively by link dispersion compensator spare, optical fiber and image intensifer; Connect successively by optical fiber, first image intensifer, link dispersion compensator spare and second image intensifer; Connect successively by link dispersion compensator spare, first image intensifer, optical fiber and second image intensifer.
In non-return to zero code fiber optic transmission system of the present invention, described preposition dispersion compensation device and rearmounted dispersion compensation device can be dispersion compensating fiber, Dispersion Compensation Grating, positive dispersion device or the prechirp realized by modulation system.
The dispersion compensation method that the present invention is used for non-return to zero code fiber optic transmission system may further comprise the steps: by modulator data to be transmitted is appended to by optical carrier that laser is exported, form the nonreturn to zero code light signal; The waveform of the nonreturn to zero code light signal of described modulator being exported by preposition dispersion compensation device is regulated, and its broadening is become the class continuous light, imports transmission link then; By rearmounted dispersion compensation device the class continuous light of described transmission link output is carried out symmetry and compress, revert to input receiver behind the nonreturn to zero code light signal.
The present invention by additional preposition, rearmounted dispersion compensation device before transmission link and afterwards, can make existing transmission system based on the NRZ sign indicating number realize surpassing transmission more than the 2000km under the situation that does not change the existing system network topology structure.
The invention will be further described below in conjunction with drawings and Examples.
Description of drawings
Fig. 1 is the structural representation of traditional non-return to zero code fiber optic transmission system;
Fig. 2 is the structural representation of non-return to zero code fiber optic transmission system of the present invention;
Fig. 3 is the schematic diagram of wherein a kind of transmission link topology unit of the present invention;
Fig. 4 and Fig. 5 are power in the transmission link shown in Figure 3 and the chromatic dispersion schematic diagrames with length variations;
Fig. 6 is the schematic diagram of second kind of transmission link topology unit of the present invention;
Fig. 7 is the schematic diagram of the third transmission link topology unit of the present invention;
Fig. 8 is the schematic diagram of the 4th kind of transmission link topology unit of the present invention.
Embodiment
System configuration of the present invention as shown in Figure 2, Fig. 2 and Fig. 1 are contrasted as can be seen, laser 1, modulator 2, transmission link 4 and the receiver 5 of the present invention in comprising traditional non-return to zero code fiber optic transmission system, before transmission link 4, also set up preposition dispersion compensation device 31, after transmission link 4, also set up the opposite rearmounted dispersion compensation device 32 of abbe number.
Wherein modulator 2 can be electric absorption, also can be the intensity modulator of MZ type LiNO3 modulator or other types; Receiver 5 can be PIN type or APD type.Here it can be dispersion compensating fiber, Dispersion Compensation Grating, positive dispersion device or the prechirp realized by modulation system that forward and backward put dispersion compensation device 31,32.
Among the present invention, the purpose that adds preposition dispersion compensation device 31 before transmission link 4 is that the waveform of NRZ light signal is regulated, and makes the redistribution of warbling in the light pulse, simultaneously NRZ light signal broadening is become the class continuous light, to realize the inhibition to nonlinear effect.Described class continuous light is amplified to the input requirement of satisfying transmission link 4 by power amplifier (not drawing in the drawings), imports transmission link 4 then.Because of preposition dispersion compensation device 31 can realize inhibition to nonlinear effect, launched power can improve greatly, thereby makes the without electronic relay transmission range obtain prolonging.
This NRZ light signal through waveform adjustment transmits in the mode near linear rule in optical fiber, and its chromatic dispersion and power can be regarded as shown in Figure 4 cyclic variation as along the variation of transmission link.Comprising a plurality of topology unit that repeat to connect in the transmission link of the present invention, is example with the topology unit structure among Fig. 3, and each topology unit is made up of the optical fiber 41, link dispersion compensator spare 43 and the image intensifer 42 that connect successively.Optical fiber NRZ light signal enters transmission in the SMF/G655 optical fiber 41 after forming the class continuous light through preposition dispersion compensation device 31 broadenings, suppress nonlinear effect by reducing the pulse power fluctuation.Though the SMF/G655 CHROMATIC DISPERSION IN FIBER OPTICS is compression class continuous light further, be reduced into original NRZ photosignal waveform, but this moment, light signal transmitted a segment length, fibre loss has caused the optical signal power decay, can ignore the influence of fiber nonlinear effect this moment, behind the link dispersion compensator spare 43 in the NRZ light signal input link, and broadened once more one-tenth class continuous light, be amplified in the next topology unit through image intensifer 42 and transmit, repeat one-period.As seen, the present invention is by preposition dispersion compensation device 31 broadening NRZ waveforms, make original NRZ system have very strong non-linear inhibition ability, reduce the accumulation of nonlinear effect in transmission link, thereby can allow that bigger optical signal power transmits, and reaches the purpose of elevator system signal to noise ratio in optical fiber.
Among the present invention, setting up the effect of placing dispersion compensation device 32 at transmission link 4 is that the class continuous light is carried out the symmetry compression, recovers original NRZ light signal, makes it be received machine in the dispersion tolerance scope and receives.
The present invention by before transmission link and increase the forward and backward dispersion compensation device 31,32 of putting afterwards, can make existing transmission system based on the NRZ sign indicating number realize surpassing transmission more than the 2000km under the situation that does not change the existing system network topology structure.Can in the NRZ of 2.5Gbit/s, 10Gbit/s, 40Gbit/s and higher or lower speed sign indicating number optical transmission system, use this technology;
In the foregoing description, each topology unit in the transmission link 4 is to be connected to form successively by optical fiber shown in Fig. 3 41, link dispersion compensator spare 43 and image intensifer 42, and in fact the present invention is also applicable to the transmission link of being made up of following topology unit:
(1) as shown in Figure 6, connect to form successively by link dispersion compensator spare 43, optical fiber 41 and image intensifer 42;
(2), as shown in Figure 7, connect to form successively by optical fiber 41, first image intensifer 42, link dispersion compensator spare 43 and second image intensifer 42;
(3), as shown in Figure 8, connect to form successively by link dispersion compensator spare 43, first image intensifer 42, optical fiber 41 and second image intensifer 42.
For the transmission link of being made up of the different topology unit, forward and backward type, index of putting dispersion compensation device 31,32 will be adjusted to some extent.
Claims (10)
1, a kind of non-return to zero code fiber optic transmission system, comprise the laser of exporting optical carrier, data to be transmitted is appended to the modulator that forms the nonreturn to zero code light signal on the described light carrier, and the transmission link that described nonreturn to zero code light signal is sent to receiver, it is characterized in that, described modulator back also be provided with described nonreturn to zero code light signal broadening become the class continuous light after the preposition dispersion compensation device of the described transmission link of input, also be provided with the rearmounted dispersion compensation device that the class continuous light compression of its output is reverted to the nonreturn to zero code light signal in described transmission link back.
2, non-return to zero code fiber optic transmission system according to claim 1 is characterized in that, described preposition dispersion compensation device equate with the dispersion measure absolute value of rearmounted dispersion compensation device and opposite in sign, chromatic dispersion gradient also to be absolute value equate and opposite in sign.
3, non-return to zero code fiber optic transmission system according to claim 1 is characterized in that, described transmission link comprises optical fiber, link dispersion compensator spare and the image intensifer that connects successively.
4, non-return to zero code fiber optic transmission system according to claim 1 is characterized in that, described transmission link comprises link dispersion compensator spare, optical fiber and the image intensifer that connects successively.
5, non-return to zero code fiber optic transmission system according to claim 1 is characterized in that, described transmission link comprises optical fiber, first image intensifer, link dispersion compensator spare and second image intensifer that connects successively.
6, non-return to zero code fiber optic transmission system according to claim 1 is characterized in that, described transmission link comprises link dispersion compensator spare, first image intensifer, optical fiber and second image intensifer that connects successively.
7, according to each described non-return to zero code fiber optic transmission system among the claim 1-6, it is characterized in that described preposition dispersion compensation device and rearmounted dispersion compensation device can be dispersion compensating fiber, Dispersion Compensation Grating, positive dispersion device or the prechirp realized by modulation system.
8, a kind of dispersion compensation method that is used for non-return to zero code fiber optic transmission system is characterized in that, may further comprise the steps:
By modulator data to be transmitted is appended to by laser and to be exported on the optical carrier, form the nonreturn to zero code light signal;
The waveform of the nonreturn to zero code light signal of described modulator being exported by preposition dispersion compensation device is regulated, and its broadening is become the class continuous light, imports transmission link then;
By rearmounted dispersion compensation device the class continuous light of described transmission link output is carried out symmetry and compress, revert to input receiver behind the nonreturn to zero code light signal.
9, method according to claim 8 is characterized in that, described preposition dispersion compensation device equate with the dispersion measure absolute value of rearmounted dispersion compensation device and opposite in sign, chromatic dispersion gradient also to be absolute value equate and opposite in sign.
10, method according to claim 8 is characterized in that, described dispersion compensation device can be dispersion compensating fiber, Dispersion Compensation Grating, positive dispersion device or the prechirp realized by modulation system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN02107653A CN1447537A (en) | 2002-03-22 | 2002-03-22 | Non-return to zero code fiber optic transmission system and dispersion compensation process |
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| CN02107653A CN1447537A (en) | 2002-03-22 | 2002-03-22 | Non-return to zero code fiber optic transmission system and dispersion compensation process |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101366209B (en) * | 2007-04-10 | 2012-10-17 | 华为技术有限公司 | Marine-cable light compensator and compensation |
| WO2019010681A1 (en) * | 2017-07-13 | 2019-01-17 | 华为技术有限公司 | Dispersion compensation method and apparatus |
| CN114866420A (en) * | 2022-04-28 | 2022-08-05 | 烽火通信科技股份有限公司 | Method and device for optimizing wavelength division transmission system |
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2002
- 2002-03-22 CN CN02107653A patent/CN1447537A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101366209B (en) * | 2007-04-10 | 2012-10-17 | 华为技术有限公司 | Marine-cable light compensator and compensation |
| WO2019010681A1 (en) * | 2017-07-13 | 2019-01-17 | 华为技术有限公司 | Dispersion compensation method and apparatus |
| CN114866420A (en) * | 2022-04-28 | 2022-08-05 | 烽火通信科技股份有限公司 | Method and device for optimizing wavelength division transmission system |
| CN114866420B (en) * | 2022-04-28 | 2023-06-09 | 烽火通信科技股份有限公司 | Method and device for optimizing wavelength division transmission system |
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